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Reviews > Sleep Gear > Sleeping Bags > REI Flash sleeping bag - 2013 > Test Report by Derek Hansen


Photo courtesy REI

REI — Flash Sleeping Bag

Test Series by Derek Hansen


NameDerek Hansen
Height5' 10" (1.78 m)
Weight170 lb (77 kg)
Email Address pix-obfuscated
City, State, CountryFlagstaff, Arizona, USA


I am a lightweight backpacker with a typical overnight pack weight of 15 lb (7 kg) and a multi-day weight of 20 lb (9 kg), each of which includes food and water. I prefer backpacking with a hammock as part of my sleep system.


Manufacturer REI, USA
Year of Manufacture 2013, made in China
Manufacturer’s Website
Listed Features
  • Designed for adult men and women
  • 800-fill-power goose down (top)
  • PrimaLoft Sport synthetic fill (bottom)
  • Waterproof, breathable shell fabric on hood, side panels and footbox increases moisture resistance in areas that often come in contact with tent side walls
  • Ripstop nylon shell fabric on the rest of the bag is treated with a Durable Water Repellent (DWR) finish to repel moisture and stains
  • Ultralight, mini-ripstop polyester lining
  • Multi-chambered hood
  • Performance fit: reduced girth at shoulders, hips, and lower legs.
  • European Norm (EN) rating for men is 32°F (0°C) and 41°F (5°C) for women
  • Differentiated drawcords (1 round, 1 flat) let you adjust hood and neck easily in the dark
  • Zipper is backed by wide, antisnag binding tape
  • The sleeping bag can be zipped to any other REI backpacking bag (women's bags zip on the right, men's on the left)
  • Includes stuff sack and storage bag
Manufacturer Recommendations

Wash in top-loading washer

Specifications What They Say What I Say
Weight 25 oz (709 g) 25.3 oz (718) (stuff sack weighs 53 g/2 oz)
Dimensions Fits up to 72 in (183 cm); 60 in (152 cm) shoulder girth; 55 in (140 cm) hip girth 82 in (208 cm) long; 27 in (69 cm) shoulder; 10 in (25 cm) foot
Colors "Cactus" (green), grey, and black
Accessories Includes cotton storage sack and stuff sack


23 Aug 2013


The REI Flash sleeping bag is a mummy-style bag with a multi-chambered hood, a left-sided full length zipper (allowing for a foot vent), and features a unique combination of 8 oz (227 g) 800-fill-power goose down on the top, and 2.2 oz (62 g) of PrimaLoft Sport synthetic insulation on the bottom. The sleeping bag has a baffled construction for the down.

The zipper is backed by a wide, anti-snagging material with a single zipper pull. According to REI, the Flash can be zipped in to other REI backpacking sleeping bags.


The Flash comes with a cotton storage bag measuring 18.5 in (47 cm) tall by 14 in (36 cm) in diameter. There is also a stuff sack included that is 14.5 in (37 cm) deep by 7 in (18 cm) in diameter.


The multi-chambered hood has differential draw cords to cinch up the chin and forehead areas independently. The forehead cord uses shock cord, which makes the hood flexible to some degree.

The bag is made with a waterproof yet breathable shell to protect the hood, side panels, and foot box. DWR-treated ripstop nylon is used on the rest of the bag.


The Flash bag is beautifully constructed with nice lines and clean cuts. Getting into the bag, it is clear the designers have "nipped and tucked" in all the right places for a streamlined "mummy" design. I felt somewhat tight around my knees and legs, making it difficult to twist to my side. It has a close feel for me, but not extreme -- just exactly what I would call a "performance fit."


The first thing that really jumped out at me when inspecting the bag was the thin layer of insulation on the bottom. I knew the bag had the synthetic PrimaLoft Sport insulation on bottom, but I wasn't expecting it to be so thin. From what I've read about this type of insulation, it is often used with clothing because of how it drapes and how little quilting is required.

One reason I volunteered to test this bag was because I intend on using it while in a hammock. Just like when sleeping on the ground, insulation gets compressed underneath in a hammock. The difference between ground sleeping and hammock sleeping is that hammocks provide excellent convective air flow underneath, which is problematic for compressed insulation (read: cold butt syndrome). In my experience, synthetic insulation compresses less than down, and when I've used synthetic bags in a hammock, I've often not needed any additional insulation underneath to stay warm. With down, however, I need a pad or an under quilt to stay warm underneath.


I was hoping that the Flash would have a little more synthetic insulation on the bottom so that I could use this bag without needing a pad or under quilt. I will test to see if this thin layer of PrimaLoft will be warm enough, or if I'll need to use a pad at certain temperatures.

Trying It Out

I didn't take notice that the zipper pulls are one-sided until I had zipped myself inside. I had snaked my arm into the bag and then realized I was a bit stuck because I couldn't find a zipper pull on the inside. REI has designed, or used, a zipper pull that can slide to be either inside or outside the bag. The next time, I remembered to turn the zipper pull so it was inside the bag the next time I zipped up.

There is also a zipper pull at the foot end, so I can unzip the foot box and vent if necessary.


I'm actually very impressed with the design of the bag. I think this is the way all sleeping bags should be made, since the bottom of the bag is compressed by the occupant, and the insulation is virtually worthless. Using a pad for insulation is essential, but putting high-performance synthetic on the bottom is a stroke of genius. Still, I have doubts that the thin slice of synthetic insulation will get me far in my hammock, so I'll likely need to bring a pad or an under quilt for needed warmth below.

The fabric feels great, the overall weight is great, and the bag stuffs down to the size of a loaf of bread. I like it.

CON—The "performance fit" is somewhat tight in spots.


21 Nov 2013


Aug 23-24: Marshall Lake, Arizona. The elevation was 6,500 ft (2,000 m). During the night, the temperature dropped into the mid-50s °F (10 °C) and we had drizzly rain all weekend.

Sep 13-14: Doney Park, Arizona. This was an overnight Boy Scout training event where I was on staff for the weekend. The elevation was 6,700 ft (2,042 m) and we were blessed with a freak rain storm that included hail and slush. The overnight low was 40°F (4°C).

Sep 20-21: Snowflake, Arizona. On this family trip I had a backyard camping trip behind our friends' home. The temperature was a warm 60°F (16°C) and the forecast was clear and warm, but someone forgot to turn off the sprinklers. Early in the morning I got drenched as powerful industrial sprayers covered me and my kids. While not technically backpacking, this trip helped prove the bag's water repellency.

Sep 27-28: Cinder Hills, Flagstaff, Arizona. The elevation was 6,700 ft (2,042 m) where I took my kids out with me on a camping trip. The temperature really dropped and overnight it sunk to a chilly 23°F (-5°C).

Nov 1-2: West Clear Creek, Arizona. This backpacking trip with my troop had an elevation change of 1,000 ft (305 m) in half a mile (0.8 km) from the trail head to the bottom of the canyon. The base elevation was 6,700 ft (2,042 m). Overnight, the temperature was 25°F (-4°C).



Camping at a campground "resort" during the Boy Scout training event.

Warmth - Overall I have enjoyed the bag and it has worked very well for me. Knowing the bag had minimal insulation on the back, I tried several different methods to keep my backside warm inside the different hammocks I used on the trail. In all the tests I've done, I've only used hammocks, but this has worked out fine with the Flash bag.

In a gathered-end hammock, I used an under quilt and I was toasty warm. On a few occasions I used a bridge hammock that provided a more 'cot'-like sleeping and I could use a regular self-inflating pad as my insulation, just like on the ground in a tent.


I used a pad in this bridge hammock, which is like sleeping in a really comfortable cot.

As the temperatures have dropped, I've had to worry about the warmth rating. On our camping trip in the Cinder Hills it got much colder than I was expecting. Thankfully I had packed a second summer-rated down top quilt and used it inside the Flash to keep warm. Without this "super" liner, I was getting chilled in the Flash bag at 23°F (-5°C).


The Flash peeking out of my Hennessy Hammock down in West Clear Creek.

My next trip I was more prepared. I had tested a very light liner that I made from some Insultex insulation. My backyard tests gave me the confidence that this liner with the Flash would get me into the 20s°F (-7°C). So on my backpacking trip into West Clear Creek, that is what I brought and I was toasty. This gave me so much confidence that I'm planning to use this insulation pair through the winter.

I should mention that for every trip I have zipped myself completely inside the Flash bag and snugged the hood tight around my face. I wore the same fleece pants, wool blend socks, and fleece/merino wool top in every trip.

Water Repellancy - Our family trip to Snowflake was suppose to be easy and uneventful. We stayed at a friends house but we elected to sleep outside in the yard as an adventure. The warmer temperatures were inviting and the cloudless sky and clear forecast meant we all slept without any rain protection. This proved our downfall as early in the morning some high-powered sprinklers kicked on and quickly drenched us. My Flash bag was soaked, but it was all I had for sleeping. After arranging all the kids back on the floor in the home, I decided to further test the wet bag indoors.

The inside of the bag was still dry, thankfully, and for the most part, the bag hadn't soaked through. By morning, the bag had dried out. I was impressed.

A few other times in my hammock I experienced some condensation on the foot end of the bag, but the DWR finish did a great job of keeping the bag from soaking through.

Zippers - My initial tests of the zipper gave me the impression of a snag-proof zip. This has not proved the case in the field. I have snagged the zipper multiple times and I'm careful to hold the material to prevent this. The single-pull zipper means I have to be more thoughtful about where I put the zipper so I can more easily get out without snaking my arm up through the head hole to grasp the zipper.

Fit and Feel - The Flash bag is a little tight in regular use. I think this is compounded more in a hammock when the sides are pulled tight against my sides. I am able to wriggle inside the bag easy enough. I think some of this is due to the soft and silky fabric that slips easily around me. I really like the feel of the fabric.

Packing - For my typical lightweight packing, I skip the stuff sack and just pack the sleeping bag directly into the bottom of my top-loading backpack. On my trip into West Clear Creek, however, I packed some heavy gear (jug of milk, cast iron skillet and lid) and used a big, external frame pack. With this pack I was "forced" to pack much of my gear externally, using stuff sacks to make it work. The Flash easily fits into the provided stuff sack with room to spare. I like the grab handle on the end that made it easy to pull the bag out when unpacking.


Outside of a little zipper issue, I'm very pleased with this bag. In my experience, it has lived up to its warmth rating, and with a liner, I can extend this bag into the winter season easily. I like the dual draw cords, making it easier to cinch the right place on the hood (face or forehead). This has been a really good bag and I like the dual insulation a lot. And I like the color.


1 Jan 2014


Nov 24-30: St. George and Orem, Utah. While visiting family during a funeral, I opted to camp outdoors multiple nights. Overnight, the low temperature was 25°F (-4°C).

Dec 26-27: Snow Canyon Red Mountain Trail, Utah. My annual Christmastime trip into Snow Canyon with my family. We backpacked a total of 5 miles (8 km) with an elevation gain of 400 ft (122 m) and an overnight low of 30°F (-1°C).


Warmth - With the temperatures continuing to drop as winter deepens, I've had to supplement the bag's insulation with a liner as well as extra clothing to stay warm. By wearing a fleece top, hat, and insulated pants, I was comfortable at the bag's lower temperature rating of 32°F (0°C). On my latest trips, I used a light synthetic liner made from Insultex (along with the extra clothing layers) that worked famously, allowing me to feel comfortable at lower temperatures.

On my backpacking trip into Snow Canyon, my feet were cold before going into bed, so I boiled up some water and put it into a Nalgene. This hot water bottle got my feet warm quickly and with the liner I was able to sleep easy through the night.

Fit and Feel - I had a really scary experience while using the sleeping bag on November 29. I had zipped myself in as I had done multiple times before. Sometime in the night I awoke with a sense of claustrophobia like I've never felt before.

I sucked in a deep breath as I oscillated between panic and surprise. I had to keep reminding myself that I was okay, that I needn't panic. After all, I had slept in this sleeping bag multiple times and I knew I was fine. Still, the panic came in waves and I had to "get out." I fumbled with the zipper, and upon finding it, tried desperately to zip out. Jam. Another jam. The zipper wasn't cooperating and I found my panic meter rising. In my half-dazed state, I was fighting against conscious rationality and subconscious irrationality, and the irrationality was winning.

I finally got the zipper down enough that I could reach an arm out and I frantically worked at it until I could get both arms out and start breathing slower, steady breaths. I've never felt that panicked inside a sleeping bag before and it worried me. Why had this happened? Regrettably, I still experience that feeling of closeness when I remember the night and I have no desire to repeat it. I don't want to zip myself up in that bag again.

Looking back at this experience, I think part of the problem was the thick layers I was wearing along with the liners I was using (I added a fleece liner that night). The Flash bag already has a trim contour and the added layers tightened the fit.


While backpacking in Snow Canyon, I used the bag as a quilt, not wanting to zip myself fully into the bag since I was using the same extra clothing layers and the liner. I was still warm and comfortable, but without the claustrophobia.

Zippers - As I mentioned already, I've had multiple zipper snags. I don't think this is anything remarkable or out of the ordinary compared with other bags, so it hasn't bothered me. In all cases I was able to work out the kink and get the sliders to work.


I think I pushed the Flash bag to the limit of comfort both in fit but also warmth. The 800 fill down performs great in both warmth but also packing.

The synthetic insulation didn't really do much for me in terms of warmth underneath. Having a pad or under quilt is essential to stay warm below. In some ways, I wonder if the synthetic insulation could be removed completely and replaced with just a sleeve where a pad could fit easily and kept in place.

The fit of the bag is tight, and when the temperatures dropped to or below the comfort rating, I had to add layers or liners to stay warm. These extra layers turned out to haunt me as I felt "stuck" in the bag with little room to move.

I would recommend using this bag for 3-season camping but would choose something roomier for winter camping.


CON—A tight fit when adding extra layers.

I would like to thank REI and for providing me with the opportunity to test this product.

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