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REI Co-op Flash 18 Review

A simple pack that's easy on the wallet, ultralight, and super popular.
REI Flash 18
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Price:  $40 List | $39.95 at REI
Pros:  Affordable, minimalist design, lightweight, super packable
Cons:  Difficult access during activities, thin waist belt and shoulder straps
Manufacturer:   REI
By Jediah Porter ⋅ Review Editor  ⋅  Jan 31, 2019
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#9 of 17
  • Comfort - 25% 4
  • Weight - 25% 10
  • Versatility - 25% 6
  • Ease of Use - 15% 5
  • Durability - 10% 4

Our Verdict

If you're looking for a lightweight pack that can accompany you on just about any mission you can dream up, AND you're on a budget, this is a great option. For just under $40, the REI Co-op Flash 18 is by far the lightest and most minimal product in our review. This pack is a minimalist's dream and scored highly in weight and versatility. With a simple top-loading design opening into a single compartment, this pack remains comfortable during a myriad of activities. It's less hiking specific than any other we tested, but it can most certainly transition between activities. This is an especially good choice if you're on a budget and need a pack to take you from urban life to the mountain then to the crag. This pack climbs well due to its narrow profile and is an excellent option for multi-pitch days and summit attempts.

This great daypack is also available in a larger size. The REI Co-op Flash 22 has more space for whatever adventure you may be on.

New Version

REI gave their Flash line of packs an update. Read on for info on the new Flash 18.

January 2019

Compare to Similar Products

Our Analysis and Test Results

The Updated Flash 18

The shape of the Flash 18 was tweaked slightly in the hopes of making loading and access even easier, and the entire bag is now an ounce lighter (9 oz instead of the previous 10 oz). It is also available in some new colors this season. See the updated Flash 18 in the left image, below. The version we tested is shown on the right.

REI Flash 18

This award winner still retails for the same great budget price of $40. We link to the new pack above, but the following review still applies to our experiences with the previous version.

Hands-On Review of the Flash 18

Check out the REI Flash 18 for one of the most versatile packs we tested, at a price you can't refuse.

The Flash is the daypack of choice for this great dane.
The Flash is the daypack of choice for this great dane.


The Flash 18 is a relatively simple pack but has what you need for many different adventures. It is hydration compatible and also comes with an external pocket including a key clip for stowing smaller items. It has a daisy chain fixed to the outside for extra external carry options, such as clipping your shoes on. There are four perimeter loops that you can clip things to, or use to secure cordage for extra lashing options. The base of the daisy chain has a loop for an ice axe, and you can connect the top with a ski strap or velcro loop. If climbing is your thing, you should take a close look at the Arc'teryx Cierzo 18.

The front bottom  and side view of this pack. Notice the vertical daisy chain that terminates in an ice axe loop. The daisy can be used to secure a blinker light or you can rig straps  bungees  or cordage to the four perimeter loops as seen in the right photo.
The front bottom, and side view of this pack. Notice the vertical daisy chain that terminates in an ice axe loop. The daisy can be used to secure a blinker light or you can rig straps, bungees, or cordage to the four perimeter loops as seen in the right photo.

Unfortunately, both the sternum strap and waist belt have pluses and minuses. The waist belt offers some stability, but the thin webbing becomes uncomfortable with heavier loads. The sternum strap does come equipped with a whistle. However, on larger torsos, it does not lower enough on the shoulder straps for a proper fit and can make you feel as though you're being choked. The good news is that both of these features are detachable. Unlike past versions of this pack, this model has nylon carry loop at the top. This makes it slightly easier to clip into the anchor if used for multi-pitch rock climbing.

The side opening front pocket was a really convenient place to store items while traveling. Just be sure to watch your back!
As you can see  the main compartment now features two small stuff pockets sized perfectly for a phone or keys.


You can't beat the low weight and low price of this bag! Weighing in at just 10 ounces, it is a great little guy to have in your arsenal, even if you never use it for an actual day hike. It is the lightest pack we reviewed. If going ultra-lightweight is your thing, be sure to look at the Granite Gear Virga 26, which is a bigger version of the Flash 18. Both packs are essentially just tubes with straps. The Virga, however, feels much bigger than the Flash and would work for quick overnight ultralight trips if needed.


This pack sits comfortably on your back as long as you don't overstuff it. Due to the frameless back panel, it is easy to overload, causing the back paneling to round. The shoulder straps are thin and breathable but are the first source of discomfort when weighing this pack down with anything over 10-15 lbs. This is an essentials-only type of pack! If you want a pack to carry more gear more comfortably, try our Editors' Choice winner, the Osprey Talon 22.

Hikers who prefer a little more access and a bit more comfort should look at the Osprey Daylite or Deuter Speed Lite. Both of these packs have more features, a front-loading design, more accessible to external pockets and more comfortable straps.

One useful tip is that you can remove the light padding in the back of the back and use it as a cushion on your lunch break. If you happen to be looking for a little more structure in the back paneling, you can easily replace this foam with a stiffer version. Even a Sam Splint works great (and then you're doubly prepared). This approach also works well with the Virga 26.

As you can see  the Flash has much wider  but more flexible shoulder straps. Our reviewers preferred these over the thin straps of the Arc'Teryx Cierzo.
As you can see, the Flash has much wider, but more flexible shoulder straps. Our reviewers preferred these over the thin straps of the Arc'Teryx Cierzo.


Due to the lightweight, minimalist design, this pack has versatility beyond a typical daypack. One of our testers ran the Grand Canyon from rim-to-rim and back with this pack and found that it worked well.

The Flash 18 also works great for bike commuting or climbing and packs down to about the size of a softball. This small size makes it easy to bring on longer backpacking trips or travels as a separate daypack. In this scenario, it can be used as a stuff sack inside a larger pack, and then removed to use as a summit pack when needed. If you don't plan on using it this way, then perhaps you should consider if this feature is worth the loss of comfort and ease of use. Other packs like the Osprey Daylite and Deuter Speed Lite are near as light as the Flash but offer better features, comfort, and ease of use.

The top loading design lets you accommodate bulky items that can be hard to pack into panel loading designs.
The top loading design lets you accommodate bulky items that can be hard to pack into panel loading designs.


Unfortunately, due to the drawstring closure on this pack, and even with the small flap designed to cover the opening, the Flash 18 was the least weather-ready pack we tested. During our 24-hour water test, the fabric seemed to shed water well. However, out of all the packs we tested, the Flash's contents were the most soaked at the end of the testing period.

We also lightly tested how much snow can work its way in through the gap created with the drawstring. During our test, the pack remained snow free, but more rigorous activity in a harsh storm would almost certainly allow snow and ice to come through.

Through months of testing, including bushwhacking through dense foliage in Red Rocks National Conservation Area, the pack survived without noticeable wear. On a side note, however, one tester hauled an older version of this model up 90 ft on the Diamond of Long's Peak. It scraped its way up, snagging along the way, and eventually arrived at the belay battered and torn, but was still usable. For what it's worth, that version and the newest version seem to be made of the same material.

Whether an avid hiker  or just playing around in the mountains  the Flash 18 is ready for anything.
Whether an avid hiker, or just playing around in the mountains, the Flash 18 is ready for anything.

Ease of Use

Since this pack features a top-loading design similar to many backpacking packs, it is easy to load and held all of our ten essentials during a pack test. There aren't many bells and whistles on this bag, which keeps it lightweight but does sacrifice some comfort and organizational features.

A 13-inch laptop will fit into this pack. However, the bag does not provide much protection for any device. While it is hydration compatible, a 3-liter bladder takes up a ton of space in the small bag, and, once it's loaded, the inside smaller mesh pocket is hard to access.

Best Application

This bag's options are pretty endless when you consider weight, price, and versatility. It's perfect for day hikes, grocery shopping, a school and gym bag, multi-pitch rock or ice climbing, and we love using it as a stuff sack inside larger packs (and then using it during summit bids).


The Flash 18 is the least expensive of the packs reviewed, but also the least durable for rigorous backcountry conditions. We find that it provides the most value for the dollar. Not only is this pack super versatile and lightweight, but it is also backed by the REI 100% satisfaction guarantee.


For the weight and price, this specialized and compact pack deserves your attention. The super simple design is ultralight and very inexpensive. Other packs are more durable and supportive of heavy loads, but for smaller missions and for tucking into the corner of your bigger bag, the Flash 18 is unique.

Jediah Porter