REI Co-op Backpacks: Complete Guide
Comprehensive technical analysis of sizing, materials, installation requirements, and manufacturer standards for rei co-op backpacks.
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In plain English
REI is a big outdoor store that is owned by its members, a bit like a credit union is owned by the people who bank there. Besides selling other companies' gear, it designs its own backpacks under the REI Co-op name and sells them mainly in its own stores and on its own website.

Its two main families of overnight packs are the Flash and the Traverse. The Flash is the lighter one, with fewer extras, for people who like to travel light. The Traverse is heavier on its own but has a sturdier frame and more pockets, so it carries a bigger load more comfortably, like choosing a sturdy hiking boot over a light sneaker.
The easiest way to choose is to think about how much you will carry. REI publishes a comfortable load for each pack. If your food, water and gear together come close to the lighter pack's limit, the sturdier one will usually feel better by the end of the day.

REI Co-op is the in-house gear brand of Recreational Equipment, Inc., the member-owned outdoor retail cooperative founded in Seattle in 1938. REI Co-op designs its own backpacks and sells them almost exclusively through REI's own stores and website rather than through third-party retailers, positioning them against brands like Osprey, Gregory and Deuter on fit, features and everyday practicality. The line spans small daypacks up through full multi-day backpacking packs, with the Flash series built around lighter empty weight and a pared-down feature set, and the Traverse series built around fuller suspension, more structure and more storage. Choosing between REI Co-op models comes down to how much weight a hiker wants to carry empty versus how much organization and support they want on the trail.
REI Co-op is known for designing its own backpacks in-house and selling them through its retail co-op rather than a wide dealer network, pairing field-tested suspension designs with a member-owned, value-focused approach. The line covers daypacks, weekend packs and multi-day backpacking packs, with Flash and Traverse as its two core backpacking families.
Because REI Co-op is the house brand of a member-owned cooperative, its product decisions answer to co-op members rather than outside shareholders, which the brand uses as part of its value pitch. Co-op members earn an annual dividend based on the cooperative's performance and each member's purchases during the year, a structure that's been part of REI's identity since the company's founding. REI Co-op backpacks are developed by an in-house design team and tested through REI's own product-development process rather than licensed from an outside manufacturer, which is part of why the brand can hold its prices below comparable packs from Osprey or Gregory. The trade-off is availability: outside of occasional outlet or resale listings, REI Co-op gear is bought directly from REI rather than compared across multiple retailers.
REI Co-op packs generally fit using either a sized back panel (offered in ranges like extra-small through extra-large) or an adjustable, hook-and-loop torso system that slides to match a hiker's measured torso length, the same C7-vertebra-to-iliac-crest measurement used across the backpacking industry. Hipbelts on most models are padded and contoured, with some lines offering interchangeable or swappable belt sizes.
REI is also known for offering in-person pack-fitting help at its physical stores, where staff measure torso length and load a pack with sandbags or weight so a hiker can feel how it carries before buying. This in-store fitting service is one of REI's most consistently cited advantages over online-only backpack retailers, since torso length and hipbelt fit matter more to comfort than brand or price. A pack that's the right size transfers most of its load to the hips regardless of which REI Co-op model it is; a pack sized wrong won't fit well no matter how good its suspension is on paper.
Buy the Flash if lighter empty weight and a simpler, roll-top design matter more than maximum organization; buy the Traverse if a fuller suspension, more pockets and comfort under heavier loads matter more than shaving ounces. Both are internal-frame backpacking packs aimed at overnight and multi-day trips, not daypacks.
| Attribute | Flash | Traverse |
|---|---|---|
| Design focus | Lighter weight, pared-down features | Fuller support, more organization |
| Closure | Roll-top main compartment | Top-lid closure |
| Frame | Spring steel frame | Tubular aluminum frame rated for loads up to 45 lbs |
| Lid and add-ons | Packmod system of removable compression straps and pockets | Fixed lid with top pocket |
| Best for | Hikers trimming pack weight without going full ultralight | Multi-day trips carrying heavier loads |
| Sizing | Adjustable torso system | Adjustable torso, men's and women's versions |
Hikers moving toward faster, lighter trips but not ready for cottage ultralight brands tend to prefer the Flash line. Hikers who prioritize comfort and storage over shaving weight, especially on trips carrying more food, water or shared gear, tend to prefer the Traverse line.
REI backs its gear with a member satisfaction guarantee that allows co-op members to return most items within a set window — historically about a year from purchase — with proof of purchase, while non-members typically get a shorter return period. This policy applies to REI Co-op backpacks the same way it applies to other REI Co-op gear.
Beyond returns, REI offers gear repair and trade-in options through its Re/Supply used-gear program at various points, letting hikers get store credit for gear they no longer use, including backpacks in resalable condition. Combined with the annual member dividend, this support structure is part of why REI Co-op packs are frequently framed as a lower-risk purchase than a one-off backpack bought from a retailer with a standard 30-day return window. None of this changes the pack's on-trail performance, but it does change the cost of getting the size or model wrong on a first purchase.
Go Deeper
Detailed companion guides for rei co-op backpacks.

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REI Co-op Flash 55 Review
An honest look at the REI Co-op Flash 55's roll-top design, adjustable suspension, and Packmod system, and which backpackers it actually suits.
REI Co-op Traverse Review
How the REI Co-op Traverse's suspension, storage capacity and fixed lid compare to lighter packs, and which multi-day backpackers it actually fits best.
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Flash versus Traverse in numbers
REI's published specs make the difference between the two families concrete. The Flash 55 uses a spring steel frame, weighs 2 lb 13 oz in size medium, holds 55 liters, and is described by REI as comfortable with loads up to 35 lb.1 It adds REI's Packmod system of removable compression straps and pockets, so you can strip parts off to save weight.1 The Traverse 60 uses a tubular aluminum frame rated for loads up to 45 lb, with extended sizing and continuous torso adjustability.2
That 10 lb gap in rated load is the practical dividing line. Gossamer Gear classes lightweight backpacking as a base weight (everything except food, water and fuel) under 20 lb, and ultralight as under 10 lb.3 Water adds up quickly, since a liter weighs about a kilogram.4 A hiker with an 18 lb base weight, four days of food and two liters of water can land near the Flash's ceiling, while the same kit sits comfortably inside the Traverse's rating. Some guides describe the Flash frame as a perimeter stay with framesheet; REI's product page describes a spring steel frame, so check the current version's spec sheet.
What the co-op structure changes, and what it does not
REI describes itself as a consumer co-operative, formed in 1938 by 23 friends, with over 25 million members.5 Its 100% Satisfaction Guarantee gives members one year for replacements or refunds, with exclusions.6 That return window reduces the cost of a sizing mistake, which matters because fit, not brand, decides comfort.
Some details on the page could not be confirmed against the verified sources used here: the Seattle founding location, how the annual member dividend is calculated, and the current Re/Supply trade-in terms. They may well be accurate, but they change over time, so check REI's own pages before relying on them.
Fabrics, PFAS and keeping the pack dry
The Flash 55 uses recycled ripstop nylon and a DWR (a water-repellent surface finish) made without PFAS, and the Traverse 60 also uses a PFAS-free DWR and includes a raincover.1,2 Those choices line up with state law: California's AB 1817 explicitly lists backpacks as textile articles and, from January 1, 2025, bars new ones containing regulated PFAS from being made or sold there.7
REI's general guidance is that pack fabrics usually have a waterproof interior coating, but water can still seep through seams and zippers, and waterproof stuff sacks inside the pack can work better than a rain cover in wind.8 For cleaning, REI says never to machine wash or machine dry a pack, and to dry it in shade or indoors because UV light degrades the fabric.9