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  • REI UpLift™ Compression technology pulls the pack load up and in, closer to your center of gravity, to improve your balance and stability
  • A 3D contoured hipbelt provides all-day comfort and stability
  • An REI Packnit™ back panel with triangle foam increases airflow and breathability
  • Water bottle pockets have secure snap closures and are positioned forward on the hipbelt so you don't have to remove the pack to grab your drink
  • Removable top lid offers customizable pack volume
  • Large mesh pocket in the front provides easy access to frequently needed items
  • Attachment loops on the front allow ice axes, tools and more to be lashed on
  • Hydration-compatible design


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Best Use Backpacking
Frame Type Internal Frame
Gear Capacity (L)
45 liters
47 liters
2 lbs. 12 oz.
2 lbs. 14 oz.
Adjustable Torso Yes
Fits Torso
18-20 inches
19-21 inches
Fits Waist/Hips
32-42 inches
34-44 inches
Material(s) 420-denier ripstop nylon
Frame Material Steel
Number of Exterior Pockets 6 + main compartment
13 x 26 x 9 inches
13 x 27 x 9 inches
Gender Men's
Rated 5 out of 5 by from Great design, no frills, and solid frame Used this pack on back-to-back weekends for backcountry skiing. Very impressed with the design, as demonstrated by the two water bottle sleeves nestled in the crux between the hip belt and pack. This is the first pack I've used of this size that makes grabbing and stowing a Nalgene easy without having to take the pack off. The fram of the pack is sturdy and a great fit (Medium, 5'9", 30" waist). The hip belt pockets are great for an iPhone, knife, and chapstick. Brain pocket is standard, front mesh stow pocket is great for easy access to layers, maps, etc. and the bottom-up cinch is a neat design to cut down on empty space or to get a snug fit to prevent gear from flopping around.
Date published: 2017-03-27
Rated 5 out of 5 by from Well thought out and comfortable! I typically use a pack around 35L but this pack was so comfortable when packed at its recommended max capacity that I decided to go with it. Its has thicker shoulder and hip pads compared to the last version and along with the uplift system so that is why it runs about 10oz heavier. Being a 45L it is a little bigger than i need but with all of the compression options I have no issues with gear sway. You can drop a reservoir internally or use the updated exterior water bottle pouches that rest in the crevice where the hip pads connect to the pack. They are simple to get to but a little tougher to get back in if you are using the soft water bottles. No real complaints about that as I am super stoked to have water bottle pockets that dont get compressed by straps or crushed entirely. The hip pockets stretch fairly well to accommodate a few small items . I use the zippered pouch for my REI 40L rain cover and it fits just fine. That cover fits the pack well too but it would be a little snug (but should still work) if the pack is filled to capacity. I have about 20 miles of use with this pack at a load-out of about 18-20 lbs and it is my favorite pack that I have used. A couple other details; you can easily go over the 45L with the expandable lid and large mesh pocket. The second hip belt pocket isnt zippered but could easily hold a phone or a couple snacks. The Zip pocket in the lid is large enough for my first aid kit, utensils, pillow, headlamp, and other small items along those lines. I am usually skeptical of store-branded products but I have had great experiences with multiple REI products and this one falls right in line with those experiences. Highly recommended if you're looking for a pack in this size range.
Date published: 2017-02-16
Rated 5 out of 5 by from Lightweight and Full of Features Got this bag and as I wanted to go from a 70 L pack down to a more lightweight set up and the difference is amazing. The front pocket is large enough for more than just a pocket for your rain jacket. Ant the Back padding and support system rival those of more expensive packs.
Date published: 2017-03-01
Rated 5 out of 5 by from Lightweight, solid support I purchased this pack with my dividend about a month and a half ago. I've since taken it on several overnighters and, without a doubt, this bag packs a punch, especially for the low price. It ditches extra weight by getting rid of organizational features that are common among mid-range packs, but honestly, I didn't find myself missing the bells and whistles. It has everything you need and nothing more. The main compartment is undivided and top-loading, but is actually quite spacious - I'm able to fit my 22 degree synthetic sleeping bag, pad, bear canister with stove inside, tent, and jacket/baselayers within the body of the bag with room to spare (I could probably get a fleece bag liner in there if I really wanted to). The brain of the pack is a wee bit small but sufficiently contains everything I need it to, and what doesn't fit slides nicely into the stretch mesh pocket on the front. The uplift compression system appears to do its job as advertised. Meanwhile, the side-pockets are sewn into the belt. which leads me to my only gripe: the pockets do not close tightly without a nalgene or large bottle inside, so you can't really use them to stow tent poles and other slim objects inside. But, this feature also makes it easy to reach a stowed water bottle, so it's a plus and a minus. All the while, it carries like a cloud. I didn't even think I'd like the off-white color but that's grown on me too. If you're looking for a small, lightweight pack that gets the job done, I'd definitely recommend this one.
Date published: 2017-04-18
Rated 5 out of 5 by from Excellent pack by REI: Ive used many packs prior I'm 5'10, 165lbs, small build but athletic. This pack in a Medium fit me perfectly. As for the pack itself, excellent execution by REI. I have tried on EVERY SINGLE HIKING PACK over 40L in REIs store, filled with roughly 25lbs of osprey weights. I can say that this pack is as comfortable than the osprey atmos variant! I just did a couple 15 mile day hikes with this pack, filled to the rim with 5 liters of water and unnecessary camping accessories, to bring my pack weight up to 33lbs. This is the UPPER LIMIT of this pack, but it still handled very well, no real shoulder pain or hip pain. You can definitely feel the aluminum frame flexing when the pack comes on and off at this weight, but once it is on your back, it is like a rock. The water bottle pockets are fantastic if you only plan to use them for water, and they accommodate REALLY wide bottles, these are NOT good if you plan to stack tent poles or other accessories in them. The stretch pocket in front holds alot of gear, and it's nice and accessible. The brain has one zippered pocket that is ample size, and the pack is perfectly sized for an Osprey 3L water bladder (what I used). The compression straps do an ample job of pulling the load into your body. The shoulder staps and hip belt are stiff at first but definitely soften up. I found this pack to be insanely comfortable despite its hard foam appearance, and I am considered "boney". This is a great sized pack for a 1-2day adventure for those who are not exactly ultralight, but can definitely span to a 2-3day pack if you are effective with your planning and packing. The left hip belt pocket holds my iphone7 with otterbox defender case, the right pocket is zippered and holds plenty of snacks. I love this pack! It rocks! BUY IT.
Date published: 2017-04-14
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Does the lid have a small mesh pocket underneath, like the flash 65?

Asked by: JustinPitt
​This pack does not have a pocket under the lid.
Answered by: REIservice
Date published: 2017-03-22

Will you guys be offering this pack in more colors?

Asked by: George Wa
As of January 2017 we do not plan to stock this pack in any other colors. All available colors are on our website.
Answered by: REIservice
Date published: 2017-02-01

Can I buy a set of Sea to Summit Hook Release Accessory Straps to add straps onto the bottom of the pack to use for a sleeping pad?

Asked by: Jooooon
The 3/4 inch Sea to Summit Hook Release Accessory Straps are a great choice for lashing a sleeping pad to the outside of this pack.
Answered by: REIservice
Date published: 2017-03-26

Is the hip belt removable?

Asked by: JanF
​No, the hip belt is sewn in.
Answered by: REIservice
Date published: 2017-02-28

Which pack cover is recommended for the Flash 45. I have the Large. Is the Duck's Back 60L the best choice?

Asked by: skl1
The 60 liter REI Co-op Duck's Back Rain Cover is a great choice.
Answered by: REIservice
Date published: 2017-04-03

Does this bag meet the carry-on requirements of airlines? If not, would it help if the bag is not completely filled? 

Asked by: Prince Akeem Joffer
If the pack is not over filled, the minimum frame dimensions are 22 x 13 x 8 inches. Please check with your airline.
Answered by: REIservice
Date published: 2017-04-01

Are they going to be a small in this pack

Asked by: Hyche
As of February 2017, we do not plan to stock a size small in this pack. All available sizes are on our website
Answered by: REIservice
Date published: 2017-04-22

Will this hold a BearVault BV500 with room to spare? An older version of the pack was pictured with one.

Asked by: Craig
​This will fit a BV500 with some room to spare.
Answered by: REIservice
Date published: 2017-03-27
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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