It is designed to be an all day pack that, according to REI, “…strikes the perfect balance between lightweight comfort and high performance…” with readily accessible water bottle pockets and a ventilated back panel. The Flash 55 sports REI’s Packmod Custom Carry System – a set of removable accessory pockets, compression straps, and tie-downs that allow for different pack setups, giving hikers the opportunity to modify their pack to suit their particular style and conditions.
- Internal-frame design
- Packmod compression straps
- Packmod pockets on the shoulder straps and hipbelt
- Roll-top closure
- Seam-taped lining in the top lid and shoulder-strap pocket
- 3D contoured hipbelt
- Ventilated back panel
- Forward-positioned water-bottle pockets with snap closures
- Exterior side pockets
- Breathable mesh front pocket
- Attachment loops on the front
- Removable top lid
- Hydration-compatible design
- Removing all Packmod accessories saves 7 oz (198 g).
- S: 14 x 29 x 12 in (36 x 74 x 30 cm)
- M: 14 x 30 x 12 in (36 x 76 x 30 cm)
- L: 14 x 31 x 12 in (36 x 79 x 30 cm)
- S: 53 liters
- M: 53 liters
- L: 53 liters
- Weight (Minimum)
- S: 2 lbs. 2oz. (0.96 kg)
- M: 2 lbs. 3 oz. (0.99 kg)
- L: 2 lbs. 4 oz. (1.02 kg)
- Weight (Maximum)
- S: 2 lbs. 9 oz. (1.16 kg)
- M: 2 lbs. 10 oz. (1.19 kg)
- L: 2 lbs. 11 oz. (1.22 kg)
- Fits Torso
- S: 18 in (46 cm)
- M: 19 in (48 cm)
- L: 20 in (51 cm)
- Fits Waist/Hips
- S: 30-40 in (76-102 cm)
- M: 32-42 in (81-107 cm)
- L: 34-46 in (86-117 cm)
- Recommended Load: 15 to 30 lbs (6.80 to 13.61 kg)
- Materials: 100-denier ripstop nylon main body; 420-denier nylon bottom
- Frame Material: Steel
- Hydration Compatible: Yes
- Gender: Men’s tested (Women’s specific fit and sizing also available)
*Editor’s Note: Unless otherwise specified, all future weights and measurements will be for Men’s size medium.
REI designed the Flash 55 for adaptability and versatility. The most unique feature of the pack is the Packmod Custom Carry System, REI’s modular selection of pockets and straps that allows the hiker to customize the backpack to suit their needs. The pack also has a roll-top closure, allowing for internal pack volumes from approximately 35 liters to 60 liters (Men’s medium). Much of my time with the pack was spent trying out different configurations with the Packmod accessories. I was curious if this could be a pack with multiple uses – from long, loaded day-hikes to overnights to multi-day treks.
Description of Field Testing
I used the Flash 55 exclusively from July through October of 2019. To test the versatility of the pack, I settled on three configurations. I used the Flash 55 in a “long-hauler” configuration on multi-day trips in Vermont and Michigan. Daily mileage on these trips peaked at 16 miles (26 km) and was generally in the seven-to-eight-mile range (11-to-13 km). When hiking, I tend to move fast and stop frequently. The longest time the Flash 55 was on my back in a given day was a total of 6 hours. Generally, the pack saw three-to-four hours of use on a given day of hiking. The pack saw use in a “weekender” configuration in Ontario, New York, and Michigan. Finally, I used the pack in a “bare-bones” setup for long-day and overnight birding and fishing trips in Michigan.
I based my performance assessment of the REI Flash 55 on the following criteria:
- Accessibility and Organization
Accessibility and Organization
The REI Flash 55 has five permanent external pockets and the capacity to add four more – the included Packmod accessory pockets – for a total of nine external pockets. There are two permanent pockets on each side of the pack, one permanent pocket on the front, two Packmod hipbelt pockets, one Packmod top lid, and one Packmod shoulder strap pocket.
The side bottle-pockets, as well as the Packmod hipbelt and shoulder pockets, are all readily accessible while wearing the pack. The Flash 55 comes with removable/reconfigurable compression and tie-down straps as well as a tool keeper that works in tandem with daisy chain loops on the front and sides of the pack.
Permanent External Pockets
- Bottle Side-Pockets
- Front Side-Pockets
- Front Pocket
Bottle Side Pockets
The Flash 55’s bottle side-pockets are forward-positioned, making it easy to hydrate while on the move. They both come equipped with a snap closure that allows for securing water bottles of smaller diameters. The bottle-pockets are constructed of stretch mesh with an elastic top.
Snapped, I found the pockets able to hold a single 700mL Smartwater bottle easily. Unsnapped, my 1180mL Klean Canteen fit well. I did try using more than one Smartwater bottle per side, but the angle of the pocket had the forward bottle top digging into my side as I hiked. The pockets held the bottles well; at no point was I worried that the bottles would slip out while scrambling, bushwacking, or carelessly taking the pack off after a day of hiking.
In actual field use, I usually ended up using one of the bottle pockets for hydration and the other for a bag of snacks and my cooking fuel. Both pockets were readily accessible while hiking, both with the pack fully loaded and with it in a long day hike configuration. It’s worth noting that the compression straps did not hinder access to the bottle side pockets. Even with the straps cinched to the maximum, I was able to grab a drink on the go. It was nice not having to struggle to hydrate while hiking.
Front Side Pockets
If I had to use one word to describe the front side pockets, that word would be deep. At their shallowest, they are 9 in (23 cm) deep. At their deepest, the pockets are 11.5 in (29 cm). The pockets are constructed of ripstop nylon, topped with elastic. They are well-designed for holding those awkward bits that do not fit easily into the main compartment of a pack.
Generally, I used one of these pockets to carry my rolled-up sleeping pad. The other I relegated to hold accessories I like having close at hand, such as my water filter and coffee setup. When in fishing mode, I slipped a tenkara rod into the pocket. When in birding mode, binoculars. On the infrequent occasions that I carry a tent, the poles fit securely in a front side-pocket. The Packmod compression straps helped secure the longer items.
The front pocket of the REI Flash 55 is constructed of stretch mesh with an elastic top. The pocket runs from 10 to 12 in (25 to 30 cm) deep, and at its widest, is 10 in (25 cm). It closes with a simple hook and loop system. The pocket is cavernous.
On multi-day treks, I found that the pocket is best used for air-drying items like a damp bivy or tarp. It also makes a handy stash pocket for a rain layer. With nothing loaded into the front pocket, the hook and loop closure had the annoying tendency to come undone. I usually had at least my rain shell in the pocket, so this wasn’t a huge issue.
The Packmod elements.
- Packmod Top Lid
- Packmod Shoulder-Strap Pocket
- Packmod Hipbelt Pockets
- Packmod Compression Straps
- Tool Keeper
Packmod Top Lid
The Flash 55 top lid is a seam-taped ripstop nylon shell with a water repellent finish, lined with REI’s Rainshield coating. The top lid has a covered, zippered closure and measures approximately 10 x 9 x 3 in (25 x 23 x 8 cm) with a capacity of approximately 5 liters. It is the heaviest of the Packmod accessories, weighing in at 2.0 oz (57g) and necessitating the use of the 0.6 oz (17 g) tie-down straps.
I found the top lid to be most useful when used on trips of three or more nights. The waterproofing was impressive, keeping contents dry during short bouts of rain as well as morning dew. It attaches easily using the four included tie-down straps. I found it handy for carrying clothing I wanted to keep dry yet accessible, such as a light pair of gloves, beanie, and down jacket. It also doubled as a pillow.
Packmod Shoulder Strap Pocket
The shoulder strap pocket is a seam-taped ripstop nylon shell with a water repellent finish lined with REI’s Rainshield waterproof coated nylon. It’s equipped with a magnetic closure and is designed for electronics that a traveler might want readily available, such as a phone or small GPS device. The pocket has a claimed capacity of 0.5 liters and measures 6.25 x 3.5 in x 1.5 in (16 x 9 x 4 cm). The weight of the pocket is 0.8 (23 g) oz.
I found this pocket to be the least useful. It attaches with one thin strap, so the pocket was prone to snagging and flopping about. It also made getting the pack on and off after rests more difficult. When mounting the Flash 55 to my back, the pouch inevitably twisted the shoulder strap around, necessitating additional adjustment. The magnetic closure is very weak. On more than one occasion, my phone slipped out of the pocket while removing the pack. I quickly set this pocket aside.
Fortunately, attachment loops on the shoulder straps exist so your favorite aftermarket shoulder strap pouches can be easily added.
Packmod Hipbelt Pockets
The REI Flash 55 comes with two detachable hipbelt pockets – one fine mesh and one ripstop nylon. The mesh pocket weighs 1.0 oz (28 g), and the ripstop nylon pocket weighs 0.8 oz (23 g). REI lists the capacity of both as 1 liter, and the dimensions are 6.6 x 4.3 in (17 x 11 cm). Both have zippered closures.
I found these pockets very practical. My regular setup has no hip belt pockets, so on my first use, I found myself at a loss as to what to pack in them. Initially, they ended up carrying what usually would go in my pockets; small knife, map, a couple of bars, and my cellphone. Then they also started to carry things that would typically get lost in a side pocket; lip balm, hand sanitizer, bug deterrent, and purification tabs. If I was on a quick fishing trip, I tossed a small box of flies, some tippet, nippers, level lines, and hemostats into the mesh pocket. If I was out for a long bird day or weekend, my notebook and pen ended up making their way into one.
The Packmod hip belt pockets saw a lot of use and held up well. My only minor gripe is that they would occasionally catch when going through thick brush. This is the price to be paid for a modular system. Having the pockets not sewn directly to the belt means corners and flaps that snag.
Packmod Compression Straps
The REI Flash 55 comes with four removable and repositionable compression straps. Fully extended, they are 17 in long (43 cm), and all four together weigh in at 0.9 oz (26 g). They are designed to be placed where the hiker needs them along the daisy chain straps on the front and sides of the pack.
While, in theory, these straps can be removed, saving nearly an ounce (28 g) in weight, I feel that they are a required part of the pack. The Flash 55 is a large volume pack, designed with multi-day treks in mind. On my longer treks with the Flash 55, as the days went on, my consumables burden became less and less. Using the compression straps kept my loads from becoming unwieldy, cinching them down closer to my center of gravity. They are also helpful for keeping longer items secured in the side pockets.
For short overnights and long day-hikes, the compression straps make the pack feel more like a 35-liter pack. They keep everything snug. I did find them a bit too long. I have struggled to come up with a three-season scenario where I would need the full 17 inches (43 cm) of strap length. In winter, I could see using them to lash snowshoes or skis to the Flash 55.
The tool keeper is a small, removable, elastic loop-and-hook closure for strapping trekking poles, an ice ax, or other tools to the pack. It weighs 0.1 oz (3 g). I used it occasionally when I got sick of carrying my poles. It held the poles well, even when moving through the brush. I could see this getting a lot more use on a winter trip.
Main Pack Body
The REI Flash 55 has a stated capacity of 55 liters (3,356 cubic inches – Men’s medium) with the roll-top cinched down and the Packmod top lid in place. With the roll-top fully extended and no Packmod lid, I estimate the capacity to be approaching 60 liters. With the roll-top in the down position, I estimate the capacity to be around 50 liters. With all of the available Packmod storage and cavernous side and back pockets, I had no problems fitting all of the gear needed for a five-day trek.
The pack is easy to load due to the stout foam back-panel and lightweight steel frame. The foam back-panel is not stiff enough for careless packing, however. Any hard or angular items should be packed away from the back-panel to avoid an uncomfortable day.
The pack has a hydration sleeve with an elastic top, a stout hook for hanging a hydration bladder, and ports for the hose on both the left and right shoulder. I found the hydration sleeve to be a snug fit with a 3-liter system. Loading the full bladder into the pack was more of a chore than I expected. I would have appreciated a slightly larger sleeve.
During my time with the pack, I primarily used three different configurations: a “bare-bones” setup for long day hikes/single night trips, a “weekender” setup for a couple of nights out, and a “long hauler” that covered a full kit for five testing-days in the field.
The “bare bones” setup is the most minimal setup I would recommend with the Flash 55. Besides the base pack, I used one tie-down strap to cinch down the roll-top and four compression straps to keep the volume in check.
If fishing was part of the trip, I added the mesh Packmod hipbelt pocket (holding a small tenkara tackle kit) to the mix. The weight of this setup was 2 lbs 4 oz (1.02 kg). Fully compressed, the pack carried with stability similar to 35-liter packs that I’ve tried. The addition of the 1 oz (28 g) mesh hipbelt pocket brings the weight to 2 lbs 5 oz (1.05 kg). Generally, I carried 12 lbs (5.44 kg) at a volume of approximately 25 liters with this setup.
My “weekender” setup extended the pack’s capacity to a couple of days. I used the barebones setup with the addition of the second Pakmod hipbelt pocket and the second set of tie-down straps. The additions were more for convenience and load management than for additional volume. The weight of this setup was 2 lbs 6 oz (1.08 kg). A typical load in this configuration was 18 lbs (8.16 kg), with a compressed volume of about 35 liters.
Finally, the ‘long hauler’ setup added the Packmod top lid into the mix. All told, this setup used four compression straps, four tie-down straps, the top lid, and the tool loop. The only Packmod accessory that didn’t get used regularly with this setup was the shoulder-strap pocket. The weight of this setup was 2 lbs 8 oz (1.13 kg). The maximum load I hauled in this configuration was 32 lbs (14.5 kg). I feel that by utilizing the top lid and fully extending the roll-top, the Flash 55’s volume can exceed 60 L.
The REI Flash 55 is a highly adaptable backpack. The Packmod Custom Carry System extends the utility of the pack. It served very well both as a weekender pack and as a multi-day trekking pack. The Flash 55 is overkill for a long day-or-single-night setup, but that isn’t the intention of the pack.
The Flash 55 comes in three sizes for both the men’s and women’s models. Unfortunately, I found the men’s sizing to be “three sizes fit most.” The reviewer pack I received was a size large, which fits a torso length of 20 in (51 cm) and a waist of 34-46 in (86 – 117 cm). In my experience with frameless packs, I’ve been able to make do with less than ideal fits. This kind of forgiveness was not the case with the Flash 55. One weekend out with the large was enough to send me to the store to grab a better fit.
At 5’8” (172 cm) tall with a 30-inch (76 cm) waist, I was sized to a small. That put me right at the bottom end of the size-range for the hipbelt, published at 30 in (76 cm) to 40 in (102 cm). The fit was a nagging issue throughout the review. Summer hikes with the pack had me struggling with the hipbelt, particularly under load. I frequently had to hike the Flash 55 back up onto my hips to take the load off of my shoulders. Thankfully my longer treks with the pack occurred in the fall when layers of clothing made the pack fit better at the hips.
Comfort was evaluated specifically for the back panel, shoulder straps, and hip belt.
The back panel is constructed of a molded, perforated foam that allows for some ventilation. It is comfortable and not overly thick. August hikes tend to be hot in Michigan, and I appreciated the slight ventilation afforded by the back panel..
The shoulder straps on the Flash 55 are 3/4 in (1.9 cm) thick foam with a ventilated mesh cover. They are equipped with two attachment loops on both straps, as well as a hydration tube loops. The attachment loops are spaced to fit the Packmod shoulder strap pocket. The Flash 55 also comes with a chest strap that is adjustable both in length and vertically (for optimal sternum positioning).
Adjustment of all the straps was easy. The webbing held its position through the buckles without any issue, including when wet or when I was moving vigorously. The same is true with the load lifters. They were set and forget.
The hip belt is an integrated part of the pack. The foam of the back panel and the hip belt are one solid piece. Like the back panel, the hip belt is lined with a lightweight, breathable mesh. My fit issues aside, I found the hip belt to be comfortable. The webbing held well through the buckle with no noticeable slipping.
Load Bearing Ability
The Flash 55 handles loads well. 30 lbs (13.61 kg) is the maximum weight that REI recommends for the Flash 55. I was comfortable hiking all day with 25 lbs (11.34 kg) in the pack. Loaded with 30 lbs (13.61 kg), I found myself a bit sore on the contact points after a day out, but I have never liked carrying that much weight. It is not a pack issue so much as a general fitness and preference issue. The compression straps keep the unused volume well contained.
The Flash 55 weighs between 35 and 42 oz (1.00 to 1.19 kg), depending on which, if any, Packmod accessories you use. I would not recommend using the pack without the compression straps in any configuration, so in reality, I found the minimum weight of the pack to be 37 oz (1.05 kg). That’s a competitive weight, particularly given the modular nature of the pack. See the comparison chart below for some examples.
Product Strengths and Limitations
- Adaptability – The Flash 55 is highly compressible and the Packmod accessories make it possible to set up the pack for different trip types.
- Comfort – Below the recommended maximum load of 30 lbs (13.61 kg), I found the pack to be comfortable thanks to the ample padding and well-designed suspension.
- Cost – At $199.00, the Flash 55 is highly price-competitive.
- Bottle-pockets – The forward-mounted bottle-pockets worked very well. The combination of the stretch mesh and the snap-fit allows for different sized bottles to be easily accessed and securely carried.
- Sizing/Fit – With only three available combinations of torso and hip measurements, the Flash 55 won’t fit everyone – but it may fit most folks.
- Shoulder-Strap Pocket (Packmod) – A poor design that could easily be improved upon with better attachments and a stronger magnetic closure.
- Overly-tight hydration sleeve – A minor complaint, but if a hiker uses a hydration bladder, it’s worth keeping in mind.
- Snagging of Packmod accessories – The price to pay for a modular system.
My last framed backpack was a Gregory Shasta, a circa 1996 behemoth of approximately 6 lbs (2.72 kg). I did a complete 360-degree turn and went frameless, now using a well-loved, lightly modded Granite Gear Virga 2. The Virga 2 is also a roll-top pack with a volume of approximately 55 liters, though it is frameless. That switch saved me 5 lbs (2.27 kg) in base weight, easily the most significant drop in weight I’ve made during my time backpacking. Since then, materials and designs have progressed, and while I am quite happy with my current setup, I was curious about what the current generation of framed packs had to offer.
The Flash 55 beats the Virga 2 on almost every count. The Flash 55 has greater accessibility and is much more adaptable. It is also much more comfortable; the Virga 2 really caps out at a load of about 20 lbs (9.07 kg) – where I was able to easily carry 25+ lbs (11.40 + kg) all day with the Flash 55. The Virga is over a pound lighter, however. It also happens to fit me better, though that is more of an individual trait.
Among currently available packs, the REI Flash 55 has a lot of competition in this weight, price, and volume market segment. Some of these options are shown in the table below, for comparison.
|REI Flash 55
|Granite Gear Crown2 60
|Gregory Optic 48
|Osprey Exos 58
|Weight (Size M)
|42 oz (1191 g)
|38 oz (1077 g)
|40 oz (1134 g)
|43 oz (1219 g)
|Load Carrying Capacity
|30 lbs (13.6 kg)
|35 lb (15.9 kg)
|30 lbs (13.6 kg)
|40 lbs (18.1 kg)
|100-denier ripstop nylon main body; 420-denier nylon bottom
|Main: 100D High-tenacity nylon with NeverWet liquid repelling treatment, Bottom: 210D High-tenacity ripstop nylon with NeverWet liquid repelling treatment
|Body: 100-denier/210-denier HD tenacity nylon; lining: 135-denier HD polyester
100D High Tenacity Nylon, Accent:
100D High Tenacity Nylon Triple Check Dobby, Bottom, 210D High Tenacity Nylon
The specifications for all the packs are similar; framed, top-loading packs with a carrying capacity of about 55 liters weighing in around two-and-a-half pounds and costing about $200 to $220. REI is clearly trying to make the Flash 55 stand out from the herd with the Packmod system. The Flash 55 is easily the most adaptable and configurable pack on the list.
The Granite Gear Crown2 60 is likely the most competitive pack in the table above. Both packs are framed, roll-top bags that are marketed towards backpackers looking to save weight on their gear. The Crown2 and the Flash 55 both offer a removable top lid. Both are priced at just under $200.00. The REI Flash 55 has more configurable storage, as the Crown2’s hip pockets are permanently attached. The Crown2 offers much greater versatility in fit, though. The hip belt sizes down to 26 in (66 cm) and, if wanted, is totally removable. It comes down to whether a hiker values configurable fit or configurable storage.
The REI Flash 55 isn’t a one-trick pony. It can do the job of multiple packs. The adjustable compression system is excellent. I didn’t feel as if I was using too much pack for the job when taking the Flash 55 out for a weekend. The capacity of this pack for multi-day treks is impressive. I found it a breeze to pack five days worth of kit with room to spare. While I tend not to pack bulky gear or food, I do almost always pack a tarp, sleeping bag, and small cook setup. Even on the rare occasions when I brought a tent along, I never felt like I was pushing the volume limits of the pack. The side and front pockets are immense, and with just a bit of consideration when selecting consumables, the Flash 55 could handle a three-season week-long journey with no concern.
As a long day-or-single-night pack, even in its most stripped-down configuration, I always felt a little “underloaded”. The Flash 55 did the job, but it was overkill. This isn’t meant to be a criticism of the Flash 55; day-pack use is a borderline proposition for a pack this size. But one of the questions I set out to answer was if this could be a pack for multiple trip-types. The Flash 55 isn’t a “quiver killer,” but it does fill multiple roles in your gear closet.
The Packmod system is a lot more useful than I thought it was going to be when I started the review. I’ve always been a “less is more” sort of guy, and at first glance, all the Packmod straps and pockets seemed gimmicky. I had done quite well without top lids, hip pockets, and cell phone shoulder holsters for years, thank you very much. But as I cycled through different configurations of the Flash 55, I found practical uses for most of the accessories.
I also found the pack to be supremely comfortable. Switching over for the summer from my frameless Granite Gear Virga 2 was game-changing. Had the REI Flash 55 actually fit me, I would continue to use it. Next season I’ll be rethinking my current setup.
My own personal fit issues and the disappointing shoulder strap pocket aside, I do recommend the REI Flash 55.
At $199.00, the Flash 55 is a good deal, so much so that I plan on purchasing the women’s version of this pack for my wife during the next REI member’s sale. She is a great example of someone who will get a ton of use out of this pack – a backpacker interested in transitioning from traditional backpacking to an ultralight setup, but who is not certain what she’ll like regarding pockets and pack organization. The combination of the pack and the Packmod accessories make for a versatile setup that allows for trying out a bunch of configurations without breaking the bank.
The Flash 55 carries a load of up to 30 lbs (13.6 kg) comfortably. As a transitioning hiker gets her kit further dialed in, the large volume and ample exterior storage will increase her range with the pack. The Flash 55 easily does the job of a weekend and a long-haul pack. If the Flash 55 fits your particular body type, it’s well worth a look.
Where to Buy
- Are you digging external pack organization? Read Andrew’s review of the Mountainsmith Zerk 40, or Dan’s review of the Atom.
- If you are interested in exploring modular exterior storage, check out Ryan’s recent blog post.
Updated November 7, 2019
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