REI Co-op Flash 55 Backpack Review
Updated:
Jan 20, 2025The REI Co-op Flash 55 ($229) is a midweight backpacking pack aimed at hikers looking to cut both weight and cost. While it’s by no means ultralight, it’s significantly more streamlined than many serious haulers while retaining a functional feature set, including an adjustable torso length, copious pockets and storage options (including a top lid), and a ventilated mesh-and-foam backpanel. The Flash’s relatively thin nylon build can’t compete with new-age materials like Dyneema or the durability of many heavy haulers, but it’s hardwearing enough for most recreational backpackers. If you keep your load around 30 pounds and under, the Flash 55 is a strong contender for one of the best values among backpacking packs.
Comfort
Organization
Weight
Durability
Water Resistance
Sustainability
Weight
2 lb. 11 oz.
Stated Load Limit
30 lb.
Fabric(s)
Ripstop nylon
Adjustable Torso
Yes
# of Pockets
9
Access
Top
Capacities
55L
Included rain cover
No
Pros
Cons
REI Co-op Flash 55
For this season's top models, see our guide to the Best Backpacking Backpacks.
During my summer of backpacking in Washington, the REI Co-op Flash 55 offered comfortable carry for loads up to about 30 pounds. The pack’s spring steel frame provides structure and distributes weight evenly across the back, while the padded hipbelt, shoulder straps, and backpanel absorb the shock of the load and wrap the body in a supportive hug. Thanks to the adjustable torso length, a near-perfect fit is achievable for almost everyone.
On a four-day trip into Washington’s Alpine Lakes Wilderness, I was testing a relatively heavy kit, including REI Co-op’s Half Dome 2 tent, Magma 15 sleeping bag, and Helix Insulated sleeping pad, along with four full days of food and a plethora of layers for the early-season conditions. The REI Co-op Flash 55 had no issues with the load; I experienced no pressure points or obvious discomfort, despite it being my first overnight foray into the mountains of summer. My one gripe is that the padding and mesh covering feel somewhat excessive and cheap, and I anticipate it will pack out more quickly than those of more premium designs. But for a $219 backpacking pack that weighs under three pounds, the Flash offers impressive comfort that will please most backpackers coming from the more traditional (read: heavier) pack world.
In terms of storage, the REI Co-op Flash 55 threads the needle between a stripped-down ultralight backpacking pack and a feature-rich heavy hauler. In other words, the weight savings don’t compromise function or convenience. The large main compartment is accessed via a roll-top, which is a welcome design for those who anticipate carrying loads of varying sizes (on our four-day trip, my 10-liter food bag dwindled to nothing). The roll-top also lets you keep or leave the top lid, which features one pocket and easily detaches via buckles. The top lid can be transformed into a hip or chest pack, and it served as my in-camp tote for items like my mug, headlamp, and playing cards.
The Flash’s external pockets are finely tuned to offer excellent on-the-go access. Both hipbelt pockets are generously sized and easily swallowed my iPhone 14, snacks for the day, sunscreen, and chapstick (one is mesh, the other is solid nylon). There’s also a cell phone pocket on the shoulder strap, though I preferred to store my phone in the hipbelt pocket and eventually removed it. I opted to hydrate via a hydration bladder (easily hung on a velcro tab, stored in the internal pouch, and threaded through one of the two hydration tube ports), but the Flash 55 also has a water bottle pocket on each side that fits a 1-liter Nalgene and has a snap closure that makes stowing and retrieving the bottle less of a fight. Finally, as I’ve grown accustomed to seeing on ultralight packs, the Flash features a drop pocket on each side (ideal for tent poles but a bit too small for an ultralight tent) and a front shove-it pocket, which is where I kept my layers for the day.
REI designed the Flash 55’s organization to be customizable, which has a mixed effect. The customizability makes the hipbelt pockets feel clunky: Each has two attachment points, adding up to a plethora of extra straps, whether or not you choose to remove the pockets. But the customizable compression straps are sleeker and can be moved around if you want to snug down a small load or affix items to the outside of your pack—and they’re relatively inconspicuous if you’re not inclined to tweak them.
The REI Co-op Flash 55 checks in at 2 pounds 11 ounces for the women’s medium, which places it smack-dab in between ultralight packs (many of which hover around 2 lb.) and more traditional designs that often fly north of 4 pounds. As a result, the Flash won’t appeal to the ultralight crowd. Still, it should be on the radar of the ultralight-curious crowd—folks who want to dabble with streamlining their backpack but aren’t quite ready to forgo all the features they’re used to (including an adjustable torso length and top lid). The Osprey Eja 58 (and men’s Exos 58) and Gregory Facet 55 (men’s Focal 58) fall into a similar category at 2 pounds 11.5 ounces and 2 pounds 8 ounces, respectively, but are more expensive at $280 and $270.
It’s worth looking at the Flash 55’s load limit alongside its weight. REI lists the limit at 30 pounds, although I can imagine the Flash being comfortable up to around 35 pounds. A number of backpacking packs achieve load limits of 30 pounds (or higher) with a lower weight. Most notably, the Hyperlite Southwest 55 checks in at just 1 pound 15.7 ounces and has a load limit of 40 pounds. Is the Flash 55 the most efficient pack in terms of its load-limit-to-pack-weight ratio? No. But compared to a pack like the Southwest, it tacks on several convenient features and a significant amount of hipbelt and backpanel padding, which might be worth the extra 11 ounces.
The Flash 55’s material set is perhaps its biggest shortcoming. While many ultralight backpacking packs incorporate new-age materials like Dyneema and Robic nylon, which are praised for their lightweight nature and tear resistance (Dyneema is also waterproof), the Flash is built with simple ripstop nylon and mesh. REI does not list the denier of this material, but our best guess is that it’s about 100-denier in the body and 420D at the base. Traditional backpacks like the Osprey Aura AG and Gregory Deva use 210D nylon for their body fabric, about twice as thick as the Flash’s. After about a dozen days of use, my Flash is still in great shape, though it developed some puncture holes at the base of each side pocket from rubbing against my tent poles.
Given its materials, I don’t recommend the Flash 55 for long-trail hikers who expect to use their pack daily for months on end or NOLS guides who live on the trail. However, it’s perfectly serviceable for recreational backpackers who get out a few times a season. And if your pack does sustain a hole, it’s not the end of the world: a little gear repair tape and seam grip can go a long way.
The REI Co-op Flash 55 features a roll-top closure and PFC-free durable water-repellent finish on its ripstop nylon, which is about as water-resistant as it gets for a non-waterproof pack. On my early-season foray into the Enchantments, the Flash protected valiantly against spitting rain, although I had to move my layers from the front shove-it pocket (which is bordered by mesh) into the pack’s body. In anything more than light moisture, however, I’d want to pack my gear in waterproof stuff sacks or use a pack cover like the REI Co-op Duck's Back.
Select icon to view details:
Longevity
Choosing durable outdoor gear and keeping it in use for longer is one of the best ways to reduce environmental impact. Our proprietary longevity rating assesses factors like overall build quality, materials, fabric denier, component durability, and real-world performance. A green check indicates that we expect the product to be long-lasting relative to its peers, a yellow check mark indicates average longevity, and a red X indicates a product that may have a limited lifespan.
PFAS-Free DWR
Durable water-repellent (DWR) finishes can contain PFAS (per- and polyfluoroalkyl substances). These highly persistent “forever chemicals” are used in outdoor gear for their strong resistance to water, oil, and heat, but are linked to environmental contamination and a range of health concerns. A green check mark indicates the product uses a PFAS-free DWR, while a red X means the DWR contains PFAS.
Recycled Materials
Recycled materials are prevalent in outdoor gear, with nylon, polyester, wool, and down among the most common, but the composition varies widely. A green check mark indicates the product is made with a substantial amount of recycled materials (100% recycled or the core fabric that makes up most of the product is recycled), a yellow check means it contains a moderate to small amount of recycled materials, while a red X means there are no recycled materials in the product.
Bluesign Approved
Bluesign Technologies, based in Switzerland, operates a third-party textile management system that ensures materials are manufactured to strict environmental, chemical, and worker safety standards. A green check mark indicates a product is either a Bluesign Product (contains at least 90% Bluesign-approved fabrics and 20-30% Bluesign-approved accessories) or features a significant amount of Bluesign-approved materials. A yellow check mark means it uses some Bluesign-approved materials but less than the aforementioned category, and a red X means there are no Bluesign-approved materials in the product.
Responsible Manufacturing
This criterion evaluates a brand’s commitment to fair wages, safe working conditions, and reducing environmental impact through certifications and programs like Fair Trade Certified, Fair Wear Foundation, Worldwide Responsible Accredited Production (WRAP), and the Fair Labor Association, while also recognizing brands that manufacture primarily in the U.S. or Europe under strict labor and environmental regulations. A green check mark indicates a brand meets our responsible manufacturing criteria, while a red X means it does not.
Recycled and/or Reduced Packaging
Packaging can add significant waste to outdoor gear purchases, so many brands work to reduce its impact by using recycled materials, incorporating Forest Stewardship Council-certified paper products, and minimizing plastic and paper use. A green check mark indicates a brand uses recycled or reduced materials across all of its packaging, a yellow check indicates moderate or limited use of recycled or reduced packaging, and a red X indicates the brand does not make either of these efforts.
Repair Services
Repair services extend the lifespan of outdoor gear and reduce overall consumption, though programs vary widely. Some brands offer comprehensive repairs for a range of issues, while others provide limited or no repair support. A green check mark indicates a robust repair program, a yellow check mark indicates limited repair services, and a red X indicates the brand does not offer repair services.
Resale and/or Recycling Services
Resale and recycling programs help keep outdoor gear in circulation longer and out of landfills, ranging from trade-in resale platforms that offer store credit to take-back initiatives that recycle products at the end of their usable life. A green check mark indicates a brand offers both resale and recycling programs, a yellow check mark indicates it offers one or the two, and a red X indicates it offers neither.
Carbon Footprint Tracking
This criterion evaluates whether a brand measures, reports, and works to reduce its greenhouse gas emissions using established frameworks such as the Higg Index, Greenhouse Gas Protocol, or The Change Climate Project. A green check mark indicates a brand publicly reports greenhouse gas emissions data, sets clearly defined reduction targets, and uses established tracking frameworks such as Higg or The Change Climate Project. A yellow check mark indicates the brand tracks emissions and outlines reduction goals but provides limited data, lacks science-based verification, or does not clearly report progress. A red X indicates the brand does not appear to track greenhouse gas emissions or provides so little information that its efforts cannot be verified.
Annual Impact Report
Annual impact reports provide transparency and accountability by outlining a brand’s sustainability efforts across areas such as material sourcing, greenhouse gas emissions, waste, water use, supply chains, and packaging. A green check mark indicates a brand publishes a detailed, brand-specific impact report that closely aligns with our sustainability criteria and leaves little room for ambiguity. A yellow check indicates a brand provides some relevant sustainability reporting but lacks detail in key areas or is covered only briefly within a parent company report. A red X indicates a brand does not regularly publish an impact report.
Tester: 5’6”, 19” torso
Size tested: Women’s medium
The women’s Flash 55 is available in three sizes that accommodate torsos ranging from 15 to 19 inches (the men’s version ranges from 17 to 21 in.). Each pack features a torso with 2 inches of adjustability, which is relatively easy to change via a rip-and-stick slider and tab (although not as sleek as the adjustment on a pack like the Osprey Eja). The Flash’s hipbelt lengths increase with the sizes (from 30 to 38 in. in the XS and 34 to 44 in. in the M), but REI also offers a combination of the short torso length and medium hipbelt for hikers with larger bodies (the men’s combines a small hipbelt with a large torso). Finally, I found the sternum strap design to be well-executed and straightforward to adjust.
At 5'6 "and with a torso length of 19", I opted for size medium (17 to 19 in. torso), which offered an ideal fit for my frame. The torso adjustability is a major benefit, allowing users to achieve a near-ideal fit—so long as you get the appropriately sized pack. On one occasion, I loaned the pack to my mother. Being three inches shorter, she lowered the torso length to 17 inches and was comfortable throughout a four-day backpacking trip.
Osprey Eja 58 ($285): The Premium Competition
At 2 pounds 11.5 ounces and with a very similar feature set, the Osprey Eja 58 (and men's Exos 58) is the Flash 55’s premium competition. There are a few reasons why this pack might be worth the $60 price bump. First, the Eja features 4 inches of torso adjustability (compared to the Flash’s 2 in.), in addition to a wider range between its two sizes (13 to 20 in. compared to the Flash’s 15 to 19 in.). The Eja also features a suspended mesh backpanel, which offers as much comfort as the Flash but with less padding and more ventilation for hot summer days. Finally, its suspension is just a skosh more robust and can accommodate loads up to 35 pounds. The two packs offer similar durability and waterproofing (or lack thereof). If you don’t mind the added cost, the Eja offers a more premium feel alongside added fit and performance benefits, but it doesn’t have the same level of customization as the Flash (e.g., the hipbelt pockets are fixed). For more, read our review of the Osprey Exos 58.
REI Co-op Flash Air 50 ($299): Could You Go Lighter?
If you’ve transitioned from being ultralight curious to a full-blown ultralighter, REI’s Flash Air 50 has probably caught your eye. The pack checks in at just 1 pound 14 ounces for the women’s medium—almost a full pound lighter than the Flash 55. It achieves this low weight via premium ultra-high-molecular-weight polyethylene ripstop nylon, a lidless design, and nothing in the way of torso adjustment. Although it features a similar spring-steel frame and foam backpanel, the Flash Air 50 is only rated to carry 25 pounds. We were impressed with the Flash Air 50 during our testing, but unfortunately, its three sizes only accommodate those with torsos between 16 and 18 inches. As a result, we hesitate to recommend the Flash Air 50 over popular ultralight packs like the ULA Equipment Circuit, which comes in four sizes that accommodate torsos ranging from 15 to 24 inches. For more, read our review of the REI Co-op Flash Air 50.
REI's Flash 55 is aimed at backpackers looking to cut both weight and cost. It's by no means ultralight but is significantly more streamlined than many serious haulers while retaining a functional feature set. The thin nylon won’t last as long as thicker or Dyneema builds.
Comfort
Organization
Weight
Durability
Water Resistance
Sustainability
Splitting the difference between minimalist UL models and fully featured haulers, the Eja is one of the best options for those curious about lightening their load. However, it’s not as durable or lightweight as many true-blue ultralight packs.
Comfort
Organization
Weight
Durability
Water Resistance
Sustainability
Taking almost a pound off of REI's lightweight Flash backpack, the Flash Air is an attempt to bring ultralight to the masses. While it hits some high notes—its padding is comfortable and it boasts plenty of organization—its subpar load limit makes it more apt for hardcore minimalists than the ultralight-curious.
Comfort
Organization
Weight
Durability
Water Resistance
Sustainability
Is the Flash 55 for You?
The REI Co-op Flash 55’s most obvious selling point is its price: At just $219, it achieves comfort and performance on par with packs that’ll run you $50 to $100 more. While not built for serious ultralight enthusiasts, it’s a wonderful option for the ultralight-curious—backpackers who want to streamline their kit without giving up the features and comfort of a traditional backpacking pack. Its size range won’t accommodate particularly short or tall hikers, and the pack’s thin materials aren’t built for months-long thru-hikes. But for recreational backpackers looking for a comfortable, relatively feature-rich yet streamlined pack, it’s one of the best values out there.
hit the trail
Backpacking Gear Guides
Gear Guide
Best Backpacking Sleeping Pads of 2026
Gear Guide
Best Backpacking Tents of 2026
Gear Guide
Best Backpacking Sleeping Bags of 2026
Gear Guide
Best Trekking Poles of 2026
curated for you