The REI Flash 45 earned below average scores in all of our metrics with the exception of features. It includes a lot of our favorite pockets and straps, but with interesting and not always useful departures from common construction.
Logging some miles with a 25 pound load in Rocky Mountain National Park.
This pack is available in medium and large torso lengths; our test model was the large version, which was appropriate for our 5' 11" lead tester.
Weight Bottom Line:
Total Weight with all modular components = 2 lb 3.5 oz
Pack stripped of components = 2 lb 0 oz
Lid = 3. 5 oz
While you could remove the frame from this pack, we do not recommend it.
The Flash's exterior pockets hold a lot of volume, but can dump out your gear when you disconnect the straps to access the main bag.
OGL Measured Volume Bottom Line:
Total Volume = 49 L
Main Bag = 35 L
Front + Side Pockets = 8 L
Lid = 6 L
Unlike all the other packs we tested, the side and front pockets on this pack are not separated, but rather form one large, continuous mesh storage pocket. More about this below in features. At 20 g/L for both max and stripped of its lid, the Flash earned one of the worst scores for average weight-to-volume ratio. Even the more fully featured Exos 48 has a better ratio.
Load Carrying Comfort
This product didn't overly impress us in carrying comfort; we judged it "Good" at carrying both 15 and 30 pound loads. The flexible Delron rod that forms the side frame doesn't function as well as more rigid minimalist frame systems for stabilizing your load.
The Flash accepts this 25 pound load with room leftover, but doesn't carry it that well.
The Flash 45 is one of the most featured models we tested, with some strange departures from common construction. The main pack closes with a simple drawstring and is topped with a removable floating lid. Unlike all the other packs we tested, the external storage is one large wrap-around mesh pocket. At first glance, it appears to be two side pockets and a main front pocket, but no, it's actually just one big external pocket. We found it hard to get our water bottles to stay put on the side. There are no lower compression straps on this pack, just one each side near the top.
The Flash has a large free-hanging pocket inside that accepts a hydration bladder and a mitten hook on a sewn-in loop at the top to secure it. A center port allows you to route the drinking hose over either shoulder.
A shoulder strap pocket is one of the awesome features on the Flash. However, we did not find the unique side pocket construction beneficial.
This pack earned a low adaptability score. While there are side compression straps and exterior lash options, we found them not very useful. If you need to get into the main pack, you must disconnect at least two of the buckles that are likely holding your externally stored gear in place. It's possible to dump your whole exterior load just because you need one item from inside the main pack. In addition, no lower compression straps mean that low volume loads carry poorly by filling the bottom of the pack.
Without compression straps for the lower portion of the main bag, smaller loads carry awkwardly, filling the bottom and leaving the upper portion of the pack empty.
The Flash 45 earned a low score for durability. We'd recommend the Gorilla or Hyperlite Mountain Gear Windrider 3400 if you want a similarly sized pack that is more durable.
This REI backpack is not the best pack for any niche we can think of. Our three award winners each fit a niche along the ultralight backpacking spectrum.
This bag is often on sale at up to half of its retail price. If your budget is very limited, it'll get the job done til you can save up for something better.
With a poor weight-to-volume ratio and the least utilitarian set of features, the REI Flash 45 scored at the bottom of our field of contenders.
If it's all you can afford, the Flash will get the job done. However, we'd recommend saving up for a better performing ultralight pack.