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  • Lightly padded stretch-mesh shoulder straps are breathable and comfy
  • Back panel is lightly padded; pad slips out for use as a sit pad
  • Hipbelt and sternum strap can be detached
  • Sternum-strap buckle doubles as a safety whistle
  • Hydration-compatible design includes a hose exit port and an internal sleeve for a reservoir (reservoir not included)
  • Drawcord closure fully covers the top opening when cinched tight
  • Pack exterior has a zippered pocket and daisy chain with ice axe loop


Mary and Lloyd Anderson were mountaineers in search of a good ice axe. Tired of ordering from Switzerland, they started the Seattle co-op in 1938 to provide gear to their climber friends—by passing around a notebook. That sense of community is still central to the co-op today, where collective expertise from REI members and store employees informs the design of our products. This is gear is built on purpose.

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Best Use Hiking
Bag Style Backpack
Frame Type Frameless
Ultralight Yes
Gear Capacity (L) 18 liters
Gear Capacity (cu. in.) 1,100 cubic inches
Weight 10 ounces
Fits Torso 16 - 19 inches
Fits Waist/Hips 26 - 42 inches
Material(s) Ripstop nylon
Pack Access Top
Number of Exterior Pockets 1 main compartment
Dimensions 16 x 9.5 x 8 inches
Gender Unisex
Rated 5 out of 5 by from Perfect for running commutes I use this bag during my running commutes home from work. This is the second pack I've run with and by far my favorite. I love the waist clip, which stops me from getting swung around by the stuff I'm hauling. The bag is super light and the exterior pocket makes it easy to pull out my wallet to pop on the BART home. The interior pockets are great for stashing keys and an eye glass case and I've managed to fit my full change of clothes, shoes, denim jacket, book and water bottle in here! I can't recommend this bag enough! I just wish that there was a pocket for my phone on the shoulder straps, that would make it truly perfect.
Date published: 2016-04-19
Rated 5 out of 5 by from My go-to for EVERYTHING I've had mine for almost 10 years now, and it's the best $30 I ever spent. I mostly use it for day hiking and traveling. My favorite - and unheralded - feature is that it actually has daisy chain INSIDE the pack. This is perfect for traveling - you can tie your wallet/passport/camera to the inside so that you don't have to worry about some thief slashing it and collecting what falls out. Oh, it's also crazy durable. I've taken this hiking and caving countless times through sharp limestone karst and after 10 years, the only thing that caused any damage was my puppy who wanted the sandwich I had stashed inside.
Date published: 2017-03-19
Rated 5 out of 5 by from Great Value Purchased mine 3 years ago for $25. I primarily use mine as a minimalist day pack for long rock climbing routes. It'll hold a 3L hydration bladder, approach shoes, jacket, food, with room left for assorted small items. It's small and light enough that you don't really notice it when climbing. Stuffed with clothing it also makes a comfortable camping pillow. It's surprisingly durable too. Negatives: The sternum strap comes off easily and I permanently lost mine years ago. Not comfortable carrying even moderately heavy loads, but that's not what this pack was designed for.
Date published: 2016-06-26
Rated 5 out of 5 by from Great for work travel and small daypack Got this to use for work travel when I need to bring a clunky laptop backpack that would be AWFUL for hiking. I can stuff this in my tiny travel duffel no problem! I really like the design details: interior pockets, water bladder sleeve, key ring (for hair ties!), and the flap that actually covers the cinch tie. Bonus that the fabric keeps out a misting rain. The only things I'd like added are mesh side pockets and thicker back panel padding, but since it's just a foam insert that can be removed I may buy some thicker material at a craft store. Otherwise, great little pack! Love the color selections and will definitely be gifting to friends and family later this year.
Date published: 2016-02-28
Rated 4 out of 5 by from Excellent Light-Weight Pack I've purchased this pack twice now. The first time I used it for all of my day hiking adventures and definitely had it over weighted most of the time. The pack itself held up, but the webbing in the straps started to tear. So I returned it and upgraded a size. But I still missed this one!! Great for going to an outdoor concert, biking to from the gym. its the perfect little pack for when you don't need that whole day or hiking/adventure trip. folds up nice to pack and take on trips/vaca's to if you are walking around all day. I love it.
Date published: 2016-03-09
Rated 5 out of 5 by from Very Comfortable and Convenient I bought this a couple weeks ago and have taken it out twice now. One pretty short hike with just a snack and sweatshirt, and on a relatively long day hike up granite peak with an extra shirt, snacks, and a 2.5 litre hydration bladder. Both times it was surprisingly comfortable and incredibly light. I look forward to packing this for day hikes in my backpacking gear too. I should also mention I'm bigger than most people, 6'3, 190 lbs, and this fits great. Pros: Incredibly comfortable, super light, packable, looks great (silver with yellow accents), works with large-ish hydration bladder. Cons: No shoulder strap clip for hydration bladder hose (easily fixable with some ingenuity)
Date published: 2016-06-30
Rated 5 out of 5 by from So far I haven't had this pack long, but so far I love it. Incredibly light and seems really well made. I had been wanting something like this for years, a daypack to stuff in my carry-on for longer trips -- for once you get to where you're going -- and this is perfect; actually a much nicer version of what I expected to find. I'm also excited about the hydration sleeve turning this into a potential bikepacking pack. So far, I've only used it as a daypack, and it handles books and whatnot with aplomb, and while the whole setup is nice and minimalist, I appreciate the internal pocket sleeves for the phone, wallet, etc. And the price is nice as well. So far, very pleased to have found such a nice, simple piece of gear I can probably use for multiple applications.
Date published: 2016-05-24
Rated 5 out of 5 by from Love this pack. Love this pack! Bought the Member pack in 2015. I use it for my daily stuff, over night trips, hikes, and camping. I love the little zipper pocket inside and use the hydration pack pocket for my tablet. It's light weight and comfortable. I recently took it on a little kayaking trip (no tablet!) and even though it got pretty wet, everything stayed dry inside and it didn't take very long for the exterior to dry. Also love that you can clip a bunch of stuff on the outside and there are little clips on the inside as well.
Date published: 2016-06-11
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I am 6-2" and weigh 250. How comfortable will this pack be for me?

Asked by: Thom
I am 5'7" and 280# -- this is a super comfortable fit for a day-pack. The shoulder straps are adjustable so you'd be able to find a good fit.
Answered by: Kristine
Date published: 2017-04-11

How large a water bag will fit in the internal sleeve of the Flash 18 and/or Flash 22?

Asked by: John Galt JR
A 3 liter (100 fl. oz.) reservoir will fit into both sizes of the Flash packs, however it is not recommended. The 3 liter size tends to take up too much room in those packs, so we recommend a 2 liter (70 fl. oz.) size or smaller.
Answered by: REIservice
Date published: 2017-05-13

What are the size specs on this pack when its fully expanded? LxWxH specs?

Asked by: nicole442
The specs listed - 16 x 9.5 x 8 inches is when the pack is fully expanded.
Answered by: REIservice
Date published: 2017-03-22

Can I fit my 3L CamelBak bladder into this bag?

Asked by: MUAC1968
The Flash 18 pack is not sized to fit a 3L hydration reservoir. A 2L size or smaller is appropriate.
Answered by: REIservice
Date published: 2017-04-03

Is the beet color more pink/purple or more red?

Asked by: capugh
The Vivid Viola color is more of a dark pink.
Answered by: REIservice
Date published: 2016-08-16

Is this backpack waterproof?

Asked by: Shenandoah
The Flash 18 Pack is water resistant.
Answered by: REIservice
Date published: 2017-02-09

Is the pack washable?

Asked by: SkiCA
We do not recommend putting a pack in a washing machine. Hand wash with warm, soapy water and a soft brush. Air dry.
Answered by: REIservice
Date published: 2017-05-22

Will this pack be offered in orange color again (as seen in video)?

Asked by: SnowLeopard36
​We have plans to try and stock the orange color again in 2017. Please call us directly for details on availability. We can be reached at 1-800-426-4840.​
Answered by: REIservice
Date published: 2017-04-11
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REI Co-op Flash series gear and clothing

Backpacking gear built for swift escapes

Our lightweight, 3-season series is now updated with clever designs, added features and smarter fabrics.

Shop REI Co-op Flash Series