REI Flash Air 50 Backpack Review

The REI Flash Air 50 Backpack is an ultralight, roll-top backpack that weighs 1 lbs 14 oz. Available in men’s and women’s sizes, it’s quite similar to the REI Flash 55 Backpack (link to our review) with its reconfigurable pack-mod accessory pocket and strap system but is about a pound lighter in weight, has a fixed length torso instead of an adjustable torso length, and does not have a top lid pocket.

Both packs are still available in REI’s online store and while the Flash 55 is about a pound heavier (2 lbs 13 oz), it has better side compression and comes with a roll top closure and a removable top lid which are capabilities that make it more suitable for winter hiking and carrying smaller volume loads in addition to larger ones.

Like many ultralight backpacks, the Flash Air 50 has a roll-top closure that buckles together on top but not along the sides. It has a large main compartment, open side pockets, and an open front stretch pocket for stuffing layers and looser items you want frequent access to during the day. The Flash Air 50 also has dedicated water bottle pockets, separate from its side pockets, a feature first introduced on REI packs about a decade ago. These are located behind the hip belt and in front of the open side pockets, making it much easier to pull out a bottle while walking. I’m surprised that other backpack companies haven’t mimicked this feature because it makes water bottles so much more accessible and requires very little extra fabric weight to add.

The Flash Air 50 also incorporates the REI Pack Mod system, which lets you customize the pack by adding accessory pockets or straps to the backpack. These include a waterproof shoulder pocket sized for a Smartphone and compression/gear attachment straps (but not the other pack mod accessories available for the Flash 55). You can also add third-party pockets to the pack if you prefer (See 10 Best Backpack Accessory Pockets.)

RELATED: 10 Best Ultralight Backpacks

Specs at a Glance

• • Volume: 50L
  • Weight (total): 1 lbs 14 oz (size medium)
  • Gender: Men’s and Women’s available
  • Frame: Internal, Wishbone-shaped spring steel
  • Torso Length: Fixed
  • Pockets: 8, including Pack Mod mesh shoulder pocket
  • Hydration ready: Yes
  • Load lifters: Yes
  • Seam-sealed: No
  • Torso Sizing: (S: 18 inches), (M: 19 inches), (L: 20 inches)
  • Hip belt Sizing: (S: 32-40 inches), (M: 34-42 inches), (L: 36-46 inches)
  • Maximum recommended load: 40 lbs (our assessment)
  • Materials: UHMWPE ripstop nylon
  • Bear Canister Compatibility: a BV475 fits horizontally at the bottom of the main compartment, while a BV500 fits horizontally but only at the top (extension collar) of the main compartment. The thin cords of the Y-strap fit nicely in the grooves of the BV500 or BV475 canisters and do not bump you in the back of the head when carried on top of the pack (above the rolltop)
  • Optional Add-on Pockets and Straps (available separately) – Waterproof shoulder pocket and extra accessory straps.

Backpack Storage and Organization

The main compartment of the Flash Air 50 is huge and will hold a lot of gear and food: it feels far larger than 50L because REI, like most larger backpack manufacturers, does not count open pockets or the extension collar in its volume computations. It has an internal reservoir hang loop, but the rest of the interior space is unstructured with top access only.  A rain cover is not included with the pack, so you’ll want to line the interior with a pack liner or trash compactor bag, particularly since the thin nylon/polyester exterior fabric does absorb moisture in rain.

The sides of the roll-top clip together on top of the pack rather than along the sides, providing less vertical compression.  I prefer packs like those from Hyperlite Mountain Gear that provide both. While the top of the pack bag has a stiffener, it’s quite flexible and only on one side of the roll top making it difficult to get a tight roll unless the pack is stuffed full, and can result in leakage in rain. There is a Y-strap that loops lover the roll top but it uses a long cord not webbing and requires that the pack bag be quite full to provide any compression.

The Flash 50 has a front (solid) stretch pocket bordered on the sides with durable mesh that makes it easy to store damp or frequently accessed items, so you don’t have to stop and open up your pack to access them or put them away. The top of that pocket has a cord lock for added security, but the slack cord hangs free and can get hung up on vegetation if you hike off-trail.

The backpack has two solid sleeves (located directly behind the hip belt pockets but attached to the pack sides) to make it easy to reach the bottles or snacks while you’re wearing the pack. The bottle sleeves are sized for tall skinny SmartWater bottles and it’s easy to pull them out. The sleeves have elastic cords to hold the bottles in place, which is particularly important when you place the pack on the ground and it falls over.

The Flash Air 50 also has side pockets behind the water bottle sleeves for holding gear and longer objects, like tent poles, chair kits, fishing poles, etc, and lashing them to the side of the pack with a compression strap. It’s an important feature, especially on a pack that will be used for long-distance trips. These pockets are not reachable when wearing the pack.

The pack comes with one optional pocket, a mesh pocket that is not waterproof, sized to hold a smartphone. It’s attached to the pack by looping a plastic toggle through a webbing strap on the shoulder strap. Earlier models of the Flash 55 had a waterproof shoulder strap pocket which was much better, but can still be purchased as an add-on. You can also add a third-party pocket, like the Gossamer Gear Shoulder Strap Pocket to the Flash 55 shoulder straps quite easily.

The zippered hip belt pockets are sewn on and not removable. Both are solid-faced and large enough to hold snacks, a Smartphone, or even a pair of fleece gloves

Backpack Compression and External Attachment System

Daisy chains run along both sides of the front stretch pocket and extend up the front seams to the top of the frame. These can be used to lash accessory gear to the front of the pack with carabiners or accessory cords but are somewhat limited because there is only one anchor point along the rear side of the pack alongside the shoulder straps. I’d prefer at least two so you could lash snowshoes or a pad to the side of the pack. While you can get by without this added attachment capability for three-season backpacking, it’s much more important if you plan to use the pack in four-season (winter) conditions when you need to carry very bulky gear on the exterior of the backpack.

Out of the box, there is one side compression cord running from a side pocket to a point just below the top of the shoulder strap. One end of this cord runs through a line loc that’s girth hitched to its attachment point, so it’s easily removable, while the other is knotted onto the corner daisy chain. I’ve found such cord-based compression to be virtually worthless for real compression and prefer webbing-based compression straps instead since they’re much wider and will compress gear.

The pack also comes with an ice axe loop at the base and an elastic shaft holder attached to one of the daisy chains. It can be used to carry an ice axe or a pair of trekking poles, tips down.

Backpack Frame and Suspension

The REI Flash Air 50 has a fixed torso length and a narrow size range from 18″-20″ in men’s torsos and 16″-18″ in women’s.  The hipbelt is not removable and is molded into the foam back panel which is covered by fine mesh providing some ventilation between the blocks of foam padding. While not as cool as a suspended mesh back panel, the pack sits very close to your torso and the well-padded and pre-curved hip belt provides outstanding load transfer to the hips, particularly when carrying a heavy or bulky load. I can carry 40 pounds comfortably with the Flash Air 50, which is much more weight than most ultralight backpacks from cottage manufacturers.

The Flash 50’s frame is a lightweight wishbone-shaped steel perimeter wire (not removable). It provides great torsional flex, so it moves with you, as well as the horizontal rigidity that is important for proper load lifter function and hip belt load transfer. The hip belt is sewn directly to the pack so that the load is carried very close to your core muscles and hip girdle for maximum efficiency, while the soft lumbar pad and pre-curved hip belt wings grip the iliac crest. I’m really quite impressed with the hip carry on the Flash Air 50, which is comfortable and does not slip down.

The hip belt closes with push-forward straps for mechanical advantage, with a single central buckle, which I prefer on packs because it can be used while wearing gloves and because it’s better for winter use when snow will clog smaller buckles.

The shoulder straps are S-shaped making them comfortable for men with load lifters. The sterum strap buckle is easy to close and slides vertically making it easy to adjust. There are three horizontal straps on each shoulder pad which are good for use with a hydration system but can also be used to attach accessory pockets.

Comparable Ultralight Backpacks

Make / Model	Weight	Fabric
Zpacks Arc Haul 60L	20.9 oz / 593g	Ultra 200
Hyperlite Mountain Gear Southwest 55	34.9 oz / 989g	Dyneema DCF
Granite Gear Crown 3 60L	32.6 oz / 1040g	Robic Nylon
Osprey Exos Pro 55	34.6 oz / 981g	UHMWPE Nylon Ripstop
ULA Circuit 68L	37.3 oz / 1038g	Robic Nylon
Gossamer Gear Mariposa 60L	30.5 oz / 865g	Robic Nylon
REI Flash 55L	45 oz / 1276g	Robic Nylon
Gregory Focal 58	41.3 oz / 1171g	Robic Nylon
Waymark Gear Lite 50	34.8 oz / 987g	EcoPak EPX200
Atom Packs Mo EP50	32.1 oz / 910g	EcoPak EPX200

Recommendation

The REI Flash Air 50 is an ultralight rolltop backpack that weighs under 2 lbs. It’s best used for 3-5 day backpacking trips where you can fill the backpack up with food, clothing, and gear but becomes a bit awkward to use for shorter trips because it has relatively poor compression or external gear attachment capabilities. It is however a good option for extended or gear-heavy trips or travel because its lightweight frame and padded hip belt provide superb load-to-hip transfer for loads up to 40 lbs. If you want a pack with a top lid and better compression or gear attachment capabilities, we also recommend the REI Flash 55 backpack which is quite similar but has a richer and more robust feature set but weighs about a pound more although it’s still under 3 lbs in weight.

Disclosure: REI donated a backpack for review.

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