Want to know what is the best locking carabiner? We've tested over 50 different lockers over the past 10 years, and this update includes 15 of the best and most popular available today. Locking carabiners come in numerous different sizes and include a variety of different locking mechanisms, such as screw gates, double action, and triple action twist locking gates. This comparative review includes all different kinds, tested by our expert climbers at climbing areas all over the world. We've used these lockers attached to our belay devices, while building multi-pitch anchors, on the end of personal anchor systems, for setting up top-ropes, and for all the myriad needs while big wall climbing on El Cap. Whether you want compact lockers or extra large HMS style, need security on your belay device or simply some solid budget choices, we have the best recommendations for you.Over the last decade plus, we've tested just about every type of climbing gear you can think of, from standard carabiners and slings to cams, nuts, and even big wall gear. Need a new rope, some new shoes, or a new harness? Our rigorous testing and review processes help get to the bottom of which products are worth your hard-earned cash.
|Price||Check Price at Backcountry|
Compare at 2 sellers
|$14.89 at REI|
Compare at 2 sellers
|$35.95 at REI|
Compare at 2 sellers
|$19.95 at REI|
Compare at 2 sellers
|Pros||Versatile, lightweight, relatively affordable, lots of gate clearance, gate security stripe||Versatile, great for use with double ropes and belaying, auto-locking gate mechanism, wide gate opening||Triple-action auto-locking gate, stainless steel insert increases durability, internal spring bar prevents cross-loading or rotation||Twist-lock is easy and fast, versatile shape, lightweight, secure||Simple design, very versatile, affordable|
|Cons||Screwgate can get stuck closed, aluminum I-beam construction wears out quicker than some||Heavy and bulky||Heavy, expensive, hard to unlock with one hand||Pricey, slightly less gate clearance than HMS style||Doesn’t prevent rotation with an ATC style belay device, a bit heavy, can be awkward on a gear loop|
|Bottom Line||The best and most versatile locker at a reasonable price||A fantastic and secure carabiner choice for belaying, rappelling, or for master points||An ideal locker for belaying, and great choice for a top-rope anchor||A favorite due to its versatile shape and very easy to open twist-locking gate design||The simplest and most versatile anti-crossloading locking carabiner|
|Rating Categories||Petzl Attache||Black Diamond RockL...||Edelrid HMS Bulletp...||Petzl Sm'D Twist-Lock||DMM Rhino|
|Overall Utility (25%)|
|Ease of Unlocking and Locking (25%)|
|Compactness and Weight (20%)|
|Gate Security (20%)|
|Gate Clearance (10%)|
|Specs||Petzl Attache||Black Diamond RockL...||Edelrid HMS Bulletp...||Petzl Sm'D Twist-Lock||DMM Rhino|
|Weight||57 g||93 g||87 g||51 g||73 g|
|Gate Closed Strength (KN)||22||24||25||23||27|
|Sideways Strength (KN)||7||8||9||8||9|
|Gate Open Strength (KN)||6||8||9||7||7|
|Gate Clearance (cm)||2.6 cm||2.5 cm||2.4 cm||2.2 cm||2.2 cm|
|Visual Locking Indicator?||Yes||Autolocking||Autolocking||Autolocking||No|
|Carabiner Shape||Pear/HMS||Large Pear/HMS||Pear/HMS||Offset-D||Offset D/HMS|
|Lock Closure Type||Screw-lock||Twistlock||Triple action Auto-lock or Screwgate||Twistlock, also comes in screw lock or triple action||Triple action, double-action, or Screwgate|
Best Overall Locking Carabiner
The Petzl Attache has long been a favorite locking carabiner, providing nearly unrivaled versatility for all types of climbing. Its pear shape means that it has a large basket that allows for clipping many ropes or other 'biners to it at once without overlap or pinching, and its very large gate clearance means that getting these items on or off is also a cinch. Made with a hot-forged, I-Beam shape, this carabiner is both surprisingly light, while also super strong. The Attache can do everything, from belaying and rappelling to using it as a master point or on the end of a daisy chain, and is both light and affordable. It is one of the most versatile lockers that we've ever used. Additionally, if you plan on spending any time on big walls these locking carabiners will give you the space you need at the anchors without weighing you down.
There are very few downsides to the Attache, but one would be the fact that it's easy to tighten the screw locking mechanism down too tight, making it difficult to unscrew. This can be avoided by recognizing that when you screw a locker closed, you are simply blocking the gate from opening, not actually joining the gate to the nose, so it doesn't need to be super tight. The Attache isn't auto-locking, meaning it's not fool-proof, but this fact is offset by a red visual indicator if the gate isn't locked. Screw gates also have other advantages, like ease of use with gloves on, and affordability. All in all, the Petzl Attache is a locker that we can't live without, and recommend that every multi-pitch climber has two or three of these when they leave the ground — although it's easy to find additional uses if you own a few more.
Read Review: Petzl Attache
Best Bang for the Buck
CAMP USA Photon Lock
The CAMP USA Photon Lock has been around for a long time, but has recently been upgraded. This locker has an offset-D shape, making it ideal for building anchors on multi-pitch climbs, or using on the end of a personal anchor system, and is also versatile enough to be used for belaying. Its hot-forged, I-beam construction helps it cut down on the weight, and indeed this is one of the lightest lockers you can buy, without sacrificing size in order to accomplish this. It also has a screw gate that is quick and easy to open and close with only a couple of revolutions, and now has a visual indicator icon printed on the gate bar so you can more easily see whether the gate is fully closed or not.
There are few downsides to this very affordable locker, but the biggest is inherent in the offset-D shape — it's simply not as versatile for rappelling as an HMS/pear shaped locker. It also has slightly less gate clearance than larger lockers, although we didn't struggle to add clove hitches or clip it into anchor points when we needed to. Finally, the gate spring squeaks a bit when opening and closing the gate, but this is more of an annoyance than a safety or quality concern. Everyone who used this locker commented on how light it is for a full-sized locker; there is no need to sacrifice size and versatility in order to shed weight on the harness. This is its principal advantage, but the other would be its super low cost, making it the first locker we recommend buying if you are on a tight budget and don’t want to make many compromises.
Read Review: CAMP USA Photon Lock
Best Offset-D Shaped Locker
Petzl Sm'D Twist-Lock
Offset-D shaped lockers, whether they are full-sized or compact, make up the bulk of the selection of lockers we take on multi-pitch routes. The best one we've tested is the Petzl Sm'D Twist-Lock, which is a lightweight, full-sized offset-D that has the added security and easy handling of a twist-locking gate. While pear shaped lockers are usually considered more versatile for belaying and rappeling, the Sm'D has a basket that is wider and flatter than most of the others we tested, ensuring there is plenty of room for two ropes to sit smoothly side-by-side when rappeling. It also works great to pair with a belay device, for building anchors, and on the end of a personal anchor system.
Honestly, we can't find anything negative to say about this great locker. Sure, it is slightly heavier than the CAMP Photon Lock, but the few extra grams come in the form of the excellent double-action twist-lock mechanism, which we think is worth the weight. If you want to save a little bit of weight, you can also buy the Sm'D in a screw gate version. It's also a bit pricier than the Photon Lock, but Petzl's quality is legendary, and we once again think the added expense is worth it and in no way out of line. This is an instance where you get what you pay for. After you've purchased a dedicated locker for your Gri-Gri or other assisted belay device, and a solid pear-shaped locker for use with an ATC on multi-pitch routes, we think the rest of your locker selection should be filled out with versatile and lightweight offset-Ds, of which the Sm'D is easily the best choice.
Read review: Petzl Sm'D Twist-Lock
Best Compact Locker
Stand at the bottom of any multi-pitch climb, clip the rack onto your harness, and notice the significant amount of extra weight, not to mention clutter, that you will have to carry up the route with you. If your intended climb is close or at your limit, then cutting your weight is crucial. The weight of the rack could conceivably make a difference in whether you send or whip. Locking carabiners are an easy place to cut weight and bulk, which is why we love compact, lightweight locking carabiners. How many lockers you need on a climb is up to you, but only one or two of these at most needs to be larger pear or HMS style lockers, the rest can, and probably should, be lighter weight lockers. The DMM Phantom Screwgate is the lightest climbing rated locker we have ever used with no-fuss handling.
As long as you aren't trying to belay or rappel with these as your main locker, we found virtually no downside to using them. With their small size, don’t expect to clip a bunch of other 'biners to them or count on them to hold multiple ropes or knots. However, they can do everything else you would need a locker for, all while weighing less and taking up far less harness space than a typical locker. Anyone who loves multi-pitch climbing and won’t settle for anything less than the best should be in the market for three or four of the DMM Phantom Screwgates.
Read Review: DMM Phantom Screwgate
Best for Durability
Edelrid HMS Bulletproof Triple FG
The friction of a weighted rope running over the inside of a locking carabiner can wear grooves into the aluminum in a surprisingly short amount of time. Exacerbating this effect is the fact that our ropes are often filled with abrasive dirt from playing outside all the time, and the fact that carabiners are now usually built with a narrower I-Beam shape to save weight while still offering the necessary strength. To combat the effects of premature wear and the need for an early retirement, the Edelrid HMS Bulletproof Triple FG employs a stainless steel insert covering the basket of the carabiner where the rope typically runs. This feature is worthy enough to make it our recommendation for durability — use it for any high-wear situations, such as belaying with an ATC, rappelling, or for setting up top-rope anchors. It also has the notable perk of including a wire-gate keeper in the crotch that ensures that it always stays oriented correctly without becoming cross-loaded. Add to that the triple-action auto-locking gate mechanism, and you have one secure locking carabiner on your hands.
One of the few downsides to this locker is its weight, but the added security features are worth it. That said, on multi-pitch routes we would likely choose to carry a lighter HMS style locker, like the Petzl Attache for belaying with. We also discovered that the triple-action gate is difficult to open with one hand. This is a locker you would want to buy for specific purposes, rather than an all-around locking carabiner. With its tough metal insert, this locker is ideal for use while rappelling or as a master-point top-roping anchor, in addition to regular belaying.
Read Review: Edelrid HMS Bulletproof Triple FG
Best for Belaying with a GriGri
Belay devices should always be attached to the belay loop of a harness with a locking carabiner for security, but have the annoying tendency to flip sideways before catching a fall, occasionally cross-loading them along the wrong axis. In order to address this problem, many companies have engineered anti-cross-loading carabiners specifically for belaying, and our favorite one that offers the simplest solution is the DMM Rhino Screwgate. This beefy yet slick locker has a small "horn" on the outside of the spine that blocks braking assist devices, such as the Petzl GriGri or Trango Vergo from sliding off of the basket, where they are intended to stay to properly orient the forces of a potential fall. It also works great to keep pulley devices such as the Petzl Micro Traxion, or ascenders such as the Camp Lift, both commonly used while top-rope soloing, oriented along the proper weight-bearing axis as well. While we tested the buttery smooth and very easy to use screw gate, this locker also comes with either double-action or triple-action auto-locking gates as well.
While we love the Rhino due to its incredible simplicity and affordability. The downside is that it doesn't prevent carabiner rotation when paired with tube-style belay devices, whose keeper loop is plenty big enough to slide over the horn. We also point out that for being a simple HMS/pear shaped locker with a small horn added on, it is a bit heavy compared to the Petzl Attache, which is nearly the same shape. That said, the Rhino is as versatile as the Attache, with the added benefit of keeping rope-catching devices oriented correctly. If we are belaying with a braking assisted device, or top-rope soloing, this is the locker we’ll have on our belay loop.
Read Review: DMM Rhino Screwgate
Why You Should Trust Us
Andy Wellman, a senior gear reviewer for the past eight years, is the expert tester who leads this review. Andy has been climbing for over 23 years and considers himself a jack of all trades. Andy has traveled the world in search of climbing adventures and continues to do so. He is a former owner and publisher of Greener Grass Publishing rock climbing guidebooks, and is the author of Stone Fort Bouldering, a guidebook to one of the finest bouldering areas the US has to offer. He has passionately spent most of his life attuning himself to the intricacies of climbing gear while tackling all disciplines, from sport to big wall, bouldering to ice. He lives in the mountains of Southern Colorado.
Besides closely monitoring changes to rock climbing gear as they happen, Andy spent about 10 hours researching over 40 different locking carabiners before choosing the 15 for inclusion in this comparative review. He then tested them by using them on his adventures and climbing road trips, including jaunts to Greece, Red Rocks, Squamish, Index, and the Bugaboos, and a whole lot of climbing at Smith Rock. He also conducts side-by-side tests, comparing different lockers one after the other for things such as the ability to tie knots to them easily (where gate clearance is often an issue), the ability to use them for multi-pitch anchors, as well as belaying with many different types of belay devices. He also forced his friends and climbing partners to use his gear, gathering outside opinions on what people like and don't like. The end result is recommendations for all types of lockers, designed for all different purposes, provided by a diverse crew with an expert lead tester.
Analysis and Test Results
Locking carabiners, or simply "lockers" for short, are carabiners designed for climbing or rigging purposes that include a mechanism that keeps the gate locked closed. It's important to recognize that by locking the gate closed, you are not joining the gate to the nose to make the carabiner stronger; these carabiners are already extremely strong. Locking them simply prevents the gate from unwanted openings, securing whatever is inside the 'biner –– whether a rope, knot, or sling –– without allowing it to escape by accident. While lockers used to come in fairly simple designs, there are now countless varieties to choose from, each with an intended purpose and emphasizing certain traits, whether it's for belaying, rappelling, attaching the rope to a fixed piece or bolt, or countless other situations. Where, when, and what type of locker to use in any given situation is up to you, but the most common uses while climbing are on your belay and rappel device, as a master point of an anchor, as the connection point for a Personal Anchoring System (PAS), and to construct equalized multi-pitch anchors.
It goes without saying that climbing is dangerous, with the consequences of making one tiny mistake, even once in your life, can result in death or injury of you or your friends. While we discuss different uses and applications for locking carabiners in this review, please don't take our purchasing advice as instruction. Consult a professional guide to learn how to safely belay and climb.
Lockers come in three types: HMS or pear style, offset-D, or compact. There are also lockers that are designed specifically for use while belaying, and include additional features to enhance this use. Lockers also come with three main styles of gate locking system: screw gates (the most common), double-action auto-locking, or triple-action auto-locking, both of which lock automatically, and require either two or three actions to unlock them before opening. We graded each locker based upon five specific metrics, described in detail below, which we weighted depending on how important that metric is for a locker's overall performance. Testing and grading are always done in comparison to the other products in the review. Rather than simply making purchases based on overall scores, we recommend analyzing your own particular needs to help you choose the right product for you.
Climbing is an expensive sport to get started in, especially as you venture into large multi-pitch climbs that require far more gear than simply getting a workout at the gym. While we don't rate products based upon their value, we think this is an important consideration before purchasing. Different shaped lockers generally work better for different purposes, so the ones that are the most versatile for multiple purposes could be considered the most valuable. We also find lighter weight carabiners to be of higher value, as the lighter they are, the more likely we are to be willing to clip them to the back of the harness, and so they will get used more.
The Petzl Attache is not only our highest-rated overall performer, but is also very versatile and surprisingly lightweight. Not only that, but the price for these classic lockers remains low, and we think they present great value. The CAMP USA Photon Lock is even less expensive, and is also very light, and conveniently full-sized. The Petzl Sm'D Twist-lock is a high-scoring, high-value locker as well. While the Edelrid HMS Bulletproof Triple FG is fairly expensive, its greatly enhanced durability means that you may have this locker for a very long time before needing to replace it, adding to its value. Beware of some of the lowest-priced lockers — while they may be cheap, the drop in performance may not be worth it when you can spend a tiny fraction more and get a far higher-performing locker.
Overall Utility takes into account how well a locker performs at its intended purpose, as well as how versatile it is. In general, belay lockers, HMS-style pear lockers, and compact/lightweight D-lockers are designed for different purposes, so we first set out determining which were the best products at performing their intended purpose, compared to the competition. However, climbing is a sport where you want to carry the least amount of weight to aid in your performance, so having a locker that can do more than one thing well is a great advantage. So we also took into account the versatility of each locker, meaning its ability to be used in more than one situation without significant drawbacks.
Among all the lockers tested, the Petzl Attache does the best job at combining function and versatility. It's easy to use, is large enough to be used for nearly any purpose, has a versatile pear-shaped basket, and is light enough to not make you think twice about bringing it on long climbs. For these reasons, it is our highest-rated HMS/pear-style locker. Among the lockers designed for belaying, we found the performance of the features on the Edelrid HMS Bulletproof Triple FG to be superior to the others. Its triple-action locking mechanism is super secure for belaying, it has an internal spring bar that keeps it properly oriented, and the stainless steel insert greatly increases longevity and decreases wear. While it's pretty heavy, we felt that it was also relatively versatile for use in anchor setups or top-roping as well. The DMM Rhino is another favorite for belaying, as it is super versatile, affordable, and prevents most devices from cross-loading. The best full-sized offset-D is the Petzl Sm'D, a top scorer when accounting for both function and versatility. Among the compact/lightweight lockers, we found that the Edelrid Pure Slider and the DMM Phantom Screwgate were roughly equal in terms of overall utility. The Pure Slider didn't function as well as a locker as the DMM Phantom, but we found it to be more versatile in a number of different situations, so scored them the same. Overall Utility accounts for 25% of a product's final score.
Ease of Unlocking and Locking
The 15 lockers tested in this review include six different styles of locking mechanism: the classic screw lock, three double-action twist auto-lockers (Petzl Sm'D, Petzl Freino, and Black Diamond RockLock Twistlock), a triple-action twist auto-locker (Edelrid HMS Bulletproof), a sliding locker (Edelrid Pure Slider), a screw gate with plastic safety bar (DMM Belay Master 2), and the double gate with single screw lock found on the Mad Rock Gemini. By repeatedly opening and closing these gates we learned that they range from very quick to relatively laborious, and super easy to requiring great dexterity. For this metric, gates that were quick and easy to open scored the highest, and ones that took longer and were more difficult scored lower. While screw gates require the same action to either lock or unlock, auto-locking 'biners snap closed and lock automatically, making them super easy to lock. However, they often require more dexterity to unlock, and can sometimes be annoying to unlock in order to simply remove them from a harness loop.
With their double-action twisting auto-lock, the Black Diamond RockLock Twistlock, Petzl Sm'D Twist-lock, and Petzl Frieno were the easiest lockers to lock, and weren't too hard to unlock either. They lock by themselves every time in a snap, and to unlock you simply turn the gate a quarter turn and open it. This can easily be accomplished with one hand almost instantly. The Edelrid Pure Slider has a tiny little sliding lock that snaps over the tip of the nose when the gate is closed, and is also very quick and easy to unlock and lock. To unlock, simply slide the lock down with the thumb as you open the gate, and it then snaps closed and locks by itself (most of the time). Among screw gate lockers, the DMM Phantom is the easiest and quickest. It needs only two full revolutions, or four half twists, of the screw gate to move from fully locked to fully unlocked, less than any other screw lock, and also features very smooth, buttery twisting action.
In contrast, we found the DMM Belay Master 2 and the Edelrid HMS Bulletproof Triple to be the slowest and most difficult to lock and unlock. In the case of the Belay Master 2, with its plastic clip that must be snapped in place after screwing closed, this is by design. But the dexterity needed to manipulate the triple action unlocking maneuver of the Edelrid Bulletproof was one we could not master with only one hand. Lower scorers among the screw gates included the Metolius Element and the Black Diamond HotForge Screwgate, both of which took around double the number of revolutions for the gate to go from fully open to closed. Ease of Unlocking and Locking accounted for 25% of a product's final score.
Compactness and Weight
Gone are the days when carabiners were made of thick, heavy steel. Today most 'biners are made of an alloy of aluminum, which is far lighter than steel but can still be engineered to meet CE testing requirements for breaking strength. Also common these days are 'biners made with an I-beam construction, rather than a fully rounded rod of metal (although round stock is still somewhat common as well). I-beam design allows engineers to remove more metal while still meeting testing certifications, thereby further lightening the load of a single 'biner. Of course, using aluminum alloys in a lighter weight construction comes with the downside that these 'biners may show wear and need to be retired sooner, but for most climbers carrying less weight per item, multiplied by all of the many trinkets we need to carry with us up the rock, makes a noticeable difference in comfort, performance, and also fun, making weight something worth paying attention to.
Compactness is another factor to consider when choosing which lockers to buy. In many cases, you simply don't need a large locker that can adequately hold a Munter-hitch (like HMS style lockers are designed to do), and having a smaller locker will not only save weight once again, but also take up less space on your harness. Why would we want our climbing gear to be smaller if possible? Well, chimney your way up into the narrows of the Steck-Salathe in Yosemite, and we think you will find your answer. To rate for compactness and lightweight, we measured each locker on our independent scale, counting grams to be more accurate, and then adjusted the scores accordingly depending on how small or large they were. Smaller and lighter meant higher scores.
The king when it comes to compactness and lightness is the DMM Phantom Screwgate, advertised as the lightest locking carabiner in the world. At 41 grams (1.45 oz.) it is lighter even than the Edelrid Pure Slider, which came in second (43 grams, 1.52 oz.), even though the Phantom comes with a screw gate, which is bulkier and more secure than the sliding lock mechanism of the Pure Slider. Also very impressive is the CAMP Photon Lock, which now weighs only 43 grams, or 1.52 oz. and yet is a full-size offset-D, rather than a more compact version. While compact is certainly worth having, the added advantages of having a larger carabiner, which makes ropework easier and adds to versatility, at the same very low weight, cannot be overlooked. Compactness and lightweight account for 20% of a product's overall score.
Let's face it, if you didn't want the gate to stay locked closed, you would just buy a wiregate carabiner. While all of these lockers are going to stay closed once they are locked, some of us have slightly less trust in the gear, or more propensity to OCD behavior, than others, making gate security an important thing to consider. Auto-locking 'biners offer the most gate security because they lock automatically when they close. If the gate is closed, you can rest assured it is locked. Screw gate lockers, on the other hand, have a large caveat: you have to remember to screw them locked. Ask any experienced climber if they have ever forgotten to screw the gate of their locker closed and you are bound to hear some stories.
With its auto-locking closure and triple-action unlocking mechanism, the Edelrid HMS Bulletproof Triple FG is the most secure locker that we tested. The BD RockLock Twistgate, the Petzl Sm'D Twist-Lock, and the Petzl Freino are also auto-locking, and while they are a bit easier to open up than the Bulletproof, it's still virtually impossible to imagine a scenario where they would open on their own. Among the screw gate lockers, the DMM Belay Master features a plastic clip that snaps over the closed, locked gate, ensuring that it cannot unscrew or open on its own, also providing a solid visual indicator. The Petzl Attache, the CAMP Photon Lock, and the Mad Rock Gemini also come with visual indicators, a solid red stripe or caution icon painted onto the gate that you can see if it is unlocked, but which becomes covered up when locked. Gate security accounts for 20% of a product's final score.
Different sizes and shapes of carabiners have different amounts of gate clearance. Gate clearance is the amount of space, at its narrowest point, between the gate and the nose when the gate is fully open. Gate clearance isn't a very important feature if you intend to simply clip one sling or rope through your locker, but when you are using a locker as a master point and have multiple ropes or knots clipped to it, then clearance can become an issue. In particular, if too many items are clipped to a single small locker, it can at times become difficult to get the gate open and slide a rope or knot out. This is why we often carry a couple of HMS-style large lockers to use as master points on multi-pitch anchors, and then top off our rack with far smaller and lighter lockers with much less carrying capacity and gate clearance.
Not surprisingly, smaller, D-shaped lockers have less gate clearance than larger, pear-shaped HMS style. We measured gate clearance with a ruler with the gate fixed open by a rubber band, and those with more clearance scored higher than those with less. We also documented the clearance of each locker in the specs table. The Petzl Attache, despite not being the single largest locker in our review, never-the-less has the most gate clearance at 2.6 centimeters. A very close second is the Black Diamond RockLock Twistgate, a huge but versatile locker that is easy to use as a masterpoint or for belaying, which has 2.5 centimeters of clearance. Perhaps unsurprisingly, the DMM Phantom has the least amount of clearance, only 1.6 centimeters. As the least important feature contributing to a locker's performance, we weighted this metric at only 10%.
Climbing gear companies manufacture all sorts of locking carabiners, most of which are designed with a certain purpose or function in mind. Choosing the right locking carabiner starts by assessing the particular situations that you expect to use it, and then narrowing the search based upon the attributes that will lead to the best performance for those situations. Most climbers own many lockers, so buying a few different types and using them in different situations can help to make the selection process easier. Happy climbing.
— Andy Wellman
Ad-free. Influence-free. Powered by Testing.
GearLab is founded on the principle of honest, objective, reviews. Our experts test thousands of products each year using thoughtful test plans that bring out key performance differences between competing products. And, to assure complete independence, we buy all the products we test ourselves. No cherry-picked units sent by manufacturers. No sponsored content. No ads. Just real, honest, side-by-side testing and comparison.Learn More