Gear Review: REI Flash 45 Backpack

REI Flash 45
REI Flash 45

NOTE: Click here to read my review of the newer, 2017 version of the REI Flash 45 backpack.

REI Flash 45
$129, 45L/2,745 c.i., 2 lbs. 3 oz. (men’s medium)
Sizes: medium (fits torsos 17-19 inches) and large (50L/3,051 c.i., 2 lbs. 4 oz., fits torsos 19-21 inches)

For most backpacking trips, when I’m not carrying gear and food for my family, I pack as light as possible and walk long days: I like to see as much wilderness as I can. For those trips, I prefer a backpack that’s light but still has decent support; I find that the virtually frameless ultralight packs with minimal support pull on my shoulders too much over the course of a 10- or 12-hour day of hiking. On a recent three-day, 65-mile hike in Yosemite, carrying a max of about 25 pounds, the Flash 45 hit that nice middle ground: lightweight, yet comfortable with the amount of weight I threw into it, and very functional.

REI Flash 45 2The suspension, consisting of an aluminum headrail with two flexible Delrin rods, shifts some of the pack weight to your hips, though I still felt some of it on my shoulders because there’s not much rigidity to the frame. The medium fit my 18-inch torso fine, but it’s not sized for people with torsos shorter than 17 inches (like many women). The flexible, padded hipbelt wrapped cleanly around my waist and supported 25 pounds well, while the mesh-covered, soft, EVA back panel, which has holes for air movement, and perforated-foam shoulder straps ventilated nicely on hot High Sierra afternoons.

The Flash 45 has all the organization I look for in a lightweight pack and nothing more to add superfluous weight. The rucksack-like main compartment swallowed a large bear canister and has enough capacity for a four-day summer hike, possibly longer, provided you have light, compact gear. The large, mesh front pocket wraps around the sides, offering generous storage that’s best for lighter items like a jacket or rainfly; full water bottles, for instance, flop around and could fall out. (Use a hydration bladder in the inside sleeve for water.) The Flash 45 has two spacious, zippered hipbelt pockets (as all packs in this category should) and quick-clip bungee loops that secure an ice axe or trekking poles. The ripstop nylon pack fabric is tough enough to toss on granite without worrying about it tearing, though you should be careful with all that external mesh.

One caveat: Don’t overload this pack. It felt fine with 25 pounds, but that’s the maximum I’d recommend carrying in it. Nonetheless, no matter how far you intend to hike every day, it’s a good ultralight or thru-hiker pack at a very good price.



BUY IT NOW You can support my work on this blog by clicking this link to buy an REI Flash 45 at

See all of my backpack reviews, including a slightly larger, more supportive, and heavier model, the men’s Deuter ACT Zero 50+15 and women’s ACT Zero 45+15 SL.

NOTE: I’ve been testing gear for Backpacker Magazine for 20 years. At The Big Outside, I review only what I consider the best outdoor gear and apparel. See all of my reviews by clicking on the Gear Reviews category at left or in the main menu.

—Michael Lanza


Gear Review: Salomon Conquest GTX Boots

Gear Review: Bosavi Headlamp


Leave a Comment