The REI Co-op Flash 55 is a lightweight internal-frame backpacking pack built around a roll-top main compartment, a minimalist single-stay suspension, and a removable lid, aimed at hikers who want to cut pack weight without moving to a full cottage-ultralight setup. It sits between REI's more structured Traverse line and the pared-down packs sold by dedicated ultralight brands.
What kind of pack is the Flash 55?
The Flash 55 is a 55-liter internal-frame backpacking pack designed for multi-day trips where keeping the empty pack weight down matters as much as comfort under load. It uses a roll-top closure instead of a traditional lid-and-drawcord design, which lets the main compartment extend or compress depending on how much gear is packed.
Roll-top closures are common on lighter backpacking packs because they remove the extra fabric and buckles a fixed lid needs, and they let the same pack handle a lighter summer load or a bulkier shoulder-season load without wasted volume. The Flash 55's frame uses a single perimeter stay paired with a lightweight framesheet rather than the dual-stay suspension found on heavier-duty packs, which keeps weight down but shifts more of the carrying job onto correct sizing and load placement.
What's the deal with the removable lid?
One of the Flash 55's distinguishing features is a removable top lid that can convert into a separate summit pack or hip pack on certain versions, letting a hiker leave the main pack at camp and carry essentials on a day trip or peak scramble. This is a design detail specific to the Flash line rather than something REI's heavier Traverse packs offer.
When the lid is left on, it functions as a normal top pocket for quick-access items like a map, headlamp or snacks. When it's removed, the main compartment can be closed with the roll-top alone, and the pack sheds a small amount of weight along with the lid. This flexibility is aimed squarely at backpackers doing multi-day trips with a base camp and day-trip component, such as a multi-night trip with a summit day built in.
Who is the Flash 55 built for?
The Flash 55 fits backpackers who already have some overnight experience and want to reduce pack weight without adopting the more spartan feature set of dedicated ultralight brands. It suits three- to five-night trips at a moderate pace, where the difference between a lighter and heavier empty pack adds up over consecutive days on the trail.
It's a less natural fit for hikers who want maximum pocket organization, a highly padded hipbelt for very heavy loads, or a fixed structured lid rather than a roll-top. Those priorities point toward REI's own Traverse line or a heavier-duty pack from Osprey or Gregory instead. Because the Flash 55 trades some structure for weight savings, it also rewards careful packing more than a heavier-frame pack does — weight needs to sit close to the back and centered over the hips for the single-stay frame to carry comfortably.
How does the Flash 55 compare to other backpacking packs?
Compared to premium ultralight packs from cottage brands, the Flash 55 offers more conventional organization — a real lid, more pockets, a padded hipbelt — at a lower price, but it won't match the lowest empty weights those brands reach with Dyneema Composite Fabric builds. Compared to REI's own Traverse or to heavier packs from Osprey and Gregory, it's lighter and simpler but offers less structure for very heavy loads.
That middle position is the point: the Flash 55 is built for hikers stepping down in weight from a traditional backpacking pack, not hikers trying to hit the lowest gram counts possible. Anyone comparing it against other 50–60 liter backpacking packs should weigh the roll-top and convertible lid against how much they value a fixed structured lid and maximum pocket count.