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Hands-on Gear Review

REI Flash 18 Review

Day Pack

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Best Buy Award
Price:   $40 List | Sale $39.95 at REI
Pros:  Affordable, minimalist design, lightweight, super packable
Cons:  Difficult access during activities, thin waist belt and shoulder straps
Bottom line:  A simple pack that's easy on the wallet, ultralight, and super popular.
Editors' Rating:     
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Manufacturer:   REI


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, then look no further. For just under $40, the REI Flash 18 receives our Best Buy Award and is by far the lightest and most minimal product in our review. This pack is a minimalist's dream, and scored the best of all the packs in weight and versatility. With a simple top-loading design opening into a single compartment, this pack remains comfortable during a myriad of activities.

The Flash 18 is an awesome lightweight pack that is less hiking specific pack than any we tested, but can most certainly transition between just about all of your activities, especially 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 a great option for multi-pitch days and summit attempts.

If you want something more substantial but still lightweight, check out the Osprey Daylite.

Looking for More Space in Your Flash?
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This great daypack is also available in a larger size; the Flash 22 has more space in your pack for whatever adventure you may be on. And while you're at it, REI also sells this sweet Special Addition Flash 18 Daypack if you're looking for some extra color.

RELATED: Our complete review of day packs

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Analysis and Hands-on Test Findings

Review by:
Jeremy Bauman & Gentrye Houghton

Last Updated:
December 2, 2016

Hands-On Review

As one of the most versatile packs we tested, and with a price you just can't refuse, the REI Flash 18 walks away with as our Best Buy award winner.

Performance Comparison

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


The Flash 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 shoes. There are four perimeter loops that you can clip things to, or use to secure some cordage for extra lashing options. The base of the daisy chain has a loop for an ice axe; 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.

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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 a little bit of 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.

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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, you should be sure to look at the Granite Gear Virga 26, which is somewhat of 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 over stuff it. Due to the frameless back panel, it is easy to overload this pack, 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 10-15lbs. 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 little more comfort should look at the Osprey Daylite or Deuter Speed Lite. Both of these packs have more features, a front loading design, easier to access external pockets, and more comfortable straps.

One useful tip is that the light amount of padding in the back panel can be removed, and it provides a great cushion to sit on during 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, or even a Sam Splint works great (and then you're doubly prepared!). This approach also works well with the Cierzo 18 and Virga 26.

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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. It also works great for bike commuting or climbing and packs down to about the size of a softball so it can be brought 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 for use as a summit pack when needed. If you don't plan on using it in this manner, than 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 nearly as light as the Flash but offer better features, comfort, and ease of use.

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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 the ability for snow to work it's way in through the gap created with the drawstring. During our test, the pack remained snow free, but surely with more rigorous activity snow and ice would come through.

Through months of testing, including bushwhacking through dense foliage in Red Rocks National Conservation Area, the pack survived without noticeable wear. One a side note, however, one tester literally hauled an older version of this pack up 90 ft on the Diamond of Long's Peak. The pack 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 with the same material. If you like this style of pack but want more durability, take a look at the Arc'teryx Cierzo 18, which has a comparable design, but is made with much more durable materials (as it has been made with climbing in mind).

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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 10 essentials during a pack test. There's not a whole lot of bells and whistles to 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 pack itself does not provide much protection to any devices. While it is hydration compatible, a 3-liter bladder takes up a ton of space in the small bag, and once the bag is loaded, the inside smaller mesh pocket is hard to access.

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Best Application

The options are pretty endless with this pack when you start balancing weight, price, and versatility. This pack is 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 it to provide the most value for the dollar. Not only is this pack super versatile and light weight, it is backed by the REI 100% satisfaction guarantee. Coming in at just under $40, the Flash 18 is our pick for the Best Buy award winner.

Other Versions

REI Flash 22 - Women's
  • Cost- $50

REI Trail 25 - Women's
  • Cost- $69.50
  • This pack is women's specific

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See the side-by-side comparison, pictured left to right: REI Flash 45, REI Flash 62, REI Flash 58 - Women's, and REI Trail 25 - Women's.
  • The Flash series of packs by REI come in an assortment of sizes for all activities
  • Lightweight packs at their various sizes
  • Affordable price for quality back packs
  • Wide Variety of colors on many of the Flash series packs
Jeremy Bauman & Gentrye Houghton

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REI $39.95

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OutdoorGearLab Member Reviews

Most recent review: December 2, 2016
Summary of All Ratings

OutdoorGearLab Editors' Rating:   
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Helpful Buying Tips
How to Choose the Best Daypack for Hiking - Click for details
 How to Choose the Best Daypack for Hiking

by Jeremy Bauman and Gentrye Houghton