REI Co-op Flash Air 50 Backpack Review
Updated:
Jan 20, 2025Weighing less than two pounds, the REI Co-op Flash Air 50 ($299) is the brand’s first true entry into the ultralight pack space. In some respects, the Flash Air is a success: It provides standout comfort thanks to plush padding, and its pocket quantity and organization are commendable. However, durability is middling and the load limit is low for an internal-frame pack of this size, which are notable drawbacks given the Flash Air’s high price tag.
Comfort
Organization
Weight
Durability
Water Resistance
Sustainability
Weight
1 lb. 13 oz.
Stated Load Limit
25 lb.
Fabric(s)
UHMWPE nylon
Adjustable Torso
No
# of Pockets
8
Access
Top
Capacities
50L
Included rain cover
No
Pros
Cons
REI Co-op Flash Air 50
For this season's top models, see our guide to the Best Backpacking Backpacks.
First impressions are important, and my initial take on the Flash Air was that this pack is amazingly comfortable for its low weight. It features ample, plush foam that runs uninterrupted from the backpanel through the hipbelt, and has wide channels for airflow—and the shoulder straps are cushy as well. The luxe padding makes the pack so easy to wear that I forgot to take it off when I stopped for breaks.
The REI Co-op Flash Air 50 has an internal spring steel frame rather than just a stiff backpanel, which is more common at this weight and found in packs such as the Mountain Laurel Designs Prophet 48. However, for a backpacking pack of this size and price, with a full suspension, the Flash Air’s load capacity is fairly low; REI rates it at 25 pounds; for comparison, the frameless Prophet 48 is rated for the same max weight. That said, I comfortably carried 27 pounds in the Flash Air during a four-day backpacking trip through Washington’s Alpine Lakes Wilderness, and have no gripes about the pack’s comfort.
Overall, I emerged from my trip in the Cascades pleased with how easily I could access items stored in the Flash Air’s plentiful pockets. But the backpack is noticeably bare bones: It lacks a top lid, and the roll-top closure is the only point of access to the main compartment. Inside is a hook-and-loop attachment for a hydration reservoir and ports that accommodate a drinking tube. As with many roll-top backpacking backpacks (like the Hyperlite Southwest), I found myself wishing for a small zippered pocket at the top that could hold keys or other small essentials.
The assortment of pockets around the main compartment is where the Flash Air shines. An increasing number of ultralight packs have hipbelt pockets, and the Flash Air thankfully follows that trend. Its two zippered hipbelt compartments are each large enough to fit a phone and snacks, yet their low profile kept them out of the way of my swinging arms and trekking poles. I kept my phone, water treatment tabs, and electrolytes in one pocket and snacks, lip balm, and sunglasses in the other.
The Flash Air has two conveniently positioned water bottle sleeves, one on each side of the pack. This was one of my favorite features, as I could access my water bottles and drink without stopping to remove the pack. Each pocket can easily fit a one-liter bottle and has elastic cords to hold items in place. Additionally, the Flash Air features two side pockets, located behind the water bottle pockets. These have compression straps for security, and I used one to stow my trekking poles and the other to hold my notepad, Kindle, and power bank.
Finally, the pack has a single, large external pocket on the back, made from the same material as the main compartment and cinched tight with a drawstring at the top. I found this drop pocket helpful for stashing items I wanted to grab as quickly as possible, namely my rain jacket and down jacket.
In addition to its pocket layout, the Flash Air features a removable cell phone pocket that attaches to the front of a shoulder strap, near the chest strap. I didn’t like how this pocket felt so I eventually removed it, but it might appeal to some hikers who don’t want to keep their phone in a hipbelt pocket. There’s also an attachment loop with an elastic drawcord above, perfect for stowing an ice axe or trekking poles.
At just 1 pound 14 ounces for the women’s medium, this is easily the lightest pack I’ve ever carried. The vast majority of packs under two pounds do not have the same comfort level and feature set as the REI Co-op Flash Air 50. For comparison, the Mountain Laurel Designs Prophet 48, a classic frameless pack, weighs 1 pound 1.5 ounces but has a lower load capacity, much less cushion, and fewer pockets; the Gossamer Gear Gorilla 50, which has an internal frame, is less cushy and still weighs an ounce more (although its max load capacity is listed at 30 pounds). Apart from not being more water resistant (the fabric lacks the impenetrable qualities of Dyneema; more on that below), I can’t think of any cons related to this pack’s weight. If your hiking philosophy is a combination of “light makes right,” but you want a full suspension and need to keep the cost under $300, the Flash Air might be the pack for you.
The Flash Air’s fabric might sound familiar—it’s made from Ultra-High Molecular Weight Polyethylene (UHMWPE), the same textile that forms the base of Dyneema Composite Fabric (DCF)—the super light, super durable textile found in many ultralight packs. However, the Flash Air’s UHMWPE isn’t paired with the backers and laminates that DCF employs to achieve its superior strength-to-weight ratio and waterproofing; thus, it doesn’t match that material in toughness or weather resistance.
However, the Flash Air’s fabric seems fairly durable and definitely outclasses a nylon fabric of the same weight (REI unfortunately does not provide a denier spec). The bottom of the pack also features a thicker, more durable section of material that has been holding up well. For $300, though, I expected higher craftsmanship: The elastic drawstring that secures the side and rear compartments came undone on my first trip, and although I tried several times, I could not feed the drawstring back into its small hole. Plus, the Flash Air’s plastic buckles and toggles seem flimsy, and I worry about them breaking in the field. While making concessions to durability is common when designers look to shave ounces, I’d prefer a backpacking pack this expensive to hold up for many hiking seasons.
The Flash Air’s UHMWPE fabric has a PFC-free durable water-repellent (DWR) coating, which helps light precipitation bead up and roll off. However, if you’re hiking in the rain for an extended period, you’ll want a rain cover. REI’s size-medium Duck's Back Pack Rain Cover ($35) will fit the Flash Air 50. Finally, the zippers on the Flash Air’s hipbelt are not water-resistant—a rare yet helpful feature I’ve seen on other packs.
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Longevity
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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
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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
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Tester: 5’8”; 19" torso
Size tested: Women’s medium
REI sells the Flash Air in both men’s and women’s versions, with three size options for each: small, medium, and large for men and XS, small, and medium for women. REI helpfully lists the torso and hipbelt dimensions for each size on its website. Unfortunately, the torso length range for the three men’s sizes is just 18 to 20 inches, while the range for women is 16 to 18. This pales in comparison to packs like the Zpacks Arc Haul UltraEXP, which fits torso sizes 16 to 23 inches. To make matters worse, the REI Co-op Flash Air’s torso length and hipbelt circumference are fixed, with no way to adjust them besides using the standard tightening/loosening straps.
I’m 5 feet 8 inches tall with a torso length of 19 inches, and I chose a women’s medium (listed as having an 18-inch torso length). This is the largest version offered for women—I was surprised to see that, at just 5’8”, I maxed out the women’s sizes. I do wish I had sized up to a men’s medium, though, as I noticed toward the end of the trip that a lot of the weight was lying on my shoulders. With a little more torso length, I could have dropped the pack down more to better sit on my hips.
REI Co-op Flash 55 ($229): A More Approachable REI Model
If you don’t feel like becoming a hardcore ultralighter and all that entails (brushing your teeth with a sawed-off toothbrush, cutting the labels off your clothes, etc.), consider the REI Co-op Flash 55. This pack weighs almost a full pound more than the Flash Air (2 lb. 12 oz. for the women’s medium), but still checks in below average for a backpacking pack. And as a tradeoff, you get more features: The Flash has a removable top lid that doubles as a waist pack, an adjustable torso that makes achieving the right fit even easier, and it comes in four sizes compared to the Flash Air’s three. Otherwise, the two packs’ designs, suspensions, and pocket layouts are extremely similar, although the larger Flash can hold up to 30 pounds and is made out of heavier 100- and 210-denier nylon. If minimizing your kit isn’t your top priority, this pack is a great option that will save you $80. For more, read our review of the REI Co-op Flash 55.
Hyperlite Southwest 55 ($420): A More Durable UL Competitor
The significant price difference between the Hyperlite Mountain Gear Southwest 55 and the Flash Air primarily stems from their materials. The Southwest is made from DCF, which resists nicks and abrasions better than the Flash Air’s unlaminated UHMWPE and is entirely waterproof—an invaluable trait that provides peace of mind no matter the weather. And while the 55-liter Southwest is a few ounces heavier (depending on colorway) and lacks the plush padding of the Flash Air, it can comfortably carry over a dozen more pounds—no joke, we’ve packed a Southwest full of about 40 pounds of climbing gear and had no issue with comfort. Organization-wise, the two packs are very similar. If you don’t mind the price bump, the Hyperlite is tough to beat for durability, weather protection, and carrying comfort. For more, read our review of the Hyperlite Southwest 40.
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
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
Load capacity, durability, and waterproofing make the Southwest a thru-hiker favorite. Drawbacks include a lack of adjustability and below-average padding, but in most other aspects, this is a top-tier ultralight backpack.
Comfort
Organization
Weight
Durability
Water Resistance
Sustainability
Is the Flash Air 50 for You?
We’re used to REI Co-op-branded products being high-value, but the REI Co-op Flash Air 50 doesn’t blow us away in that regard. You can find a lot of ultralight packs for around $300—including the ULA Equipment Circuit 68L ($300) and Gossamer Gear Mariposa 60 ($315)—and the Flash Air by no means stands out from this competition. Sure, it has a low weight, but if you’re that serious about a few ounces, you’re probably willing to spend $120 more for the Hyperlite Mountain Gear Southwest or fork over another $100 for the Zpacks Arc Haul Ultra. The Flash Air 50 doesn’t match up to the carrying comfort or load limit of most ultralight backpacking packs, and its durability isn’t anything to write home about. We can definitely see its appeal for some hikers, especially those who don’t want to skimp on comfort and organization even as they pare down their kit. But for experienced ultralighters who put their gear through the wringer, there are similar models from smaller brands that offer more bang for your buck.
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