REI Flash All-Season Insulated Air Sleeping Pad

The REI Flash four-season pad outcompetes nearly every other pad in its class but its one flaw is a serious one; evidence suggests that many of them leak at the heat welded seams.

Let me start by saying, the REI Flash All Season Pad has exceeded all of my expectations. It’s warm, really warm. I’ve used the pad this past summer in Northern MN where temps are consistently in the low 50's at night. Each time, the pad kicks back so much heat that I have to unzip my sleeping bag (I have used a 20°F bag in conjunction with the pad). The inside of the pad has a layer of synthetic fiber (Primaloft like).

In addition, the pad incorporates a layer of reflective mylar like material. Together, they create a very effective shield against the transfer of energy away from your body and into the ground. I think the genius of the design is that the reflective mylar type layer is isolated between two pockets of air. The reflective layer is great at blocking radiant (movement of energy through air or vacuum) heat but not effective to block conductive (touching) heat. By situating the reflective layer between two open spaces, conductive energy transfer is greatly reduced.

What I’ve found in the past is that pressed welds lack any insulation and allow your heat to transfer away from you.
These welded gaps between the inflated areas are heat sinks. The flash has these areas but they don’t seem to affect its ability to keep me warm in summer and fall regardless of what I’m sleeping on. I can’t really say how the pad will fare in the dead of winter on snow, ice, or frozen ground, but so far, I’m always warm. 

My version is the long/wide and it covers the complete underside of my body. I even have room to squirm without leaving the pad. (78" x 25" x 2")

Even though the pad has a mylar layer inside of it, it’s quiet. There are no unpleasant sounds as you toss and turn. I’m guessing that this is due to the extra primaloft that is adhered to the otherwise noisy reflective layer. I also have the three-season Flash and this model tends to be quieter.

The material does not prevent sliding, so shifting may be an issue for some. The problem is solved by squeezing a few drops of seam seal on both sides of the pad. This prevents the pad from sliding around the floor of the tent and keeps your sleeping bag in place. 

The pad packs down to slightly larger than a 32-oz bottle. 

The deflation and inflation valves fit standard hand pump couplings.
The pad inflates with 12 pumps or 12 big breaths. I tend not to blow my own breath into my pads because the added moisture can build up and cause deterioration and reduce R-value (wet conducts energy at a much higher rate than dry). I will usually fill a medium trash bag with air and then inflate my pads with the dry air. 

The purge valve on the pad allows air to enter but not escape. The valve is effective. There’s also a small depression knob in the valve. After inflating the pad, you can lay on the pad and then depress the valve. It will release air until you reach your desired comfort level. It is easy and and works like a charm. 
Both the inflation and deflation plugs have a rubber washer/gasket. 

The deflation valve allows you to “pull the plug” and deflate the pad within five seconds. This lets you quickly roll up your pad. 

The pad is 2 inches thick when inflated. This allows me to sleep in comfort.  

With all of the accolades the Flash has amassed in this review, the purchase of one might seem like a no-brainer…. Not so fast! There is one very significant drawback to the Flash. The heat pressed seams have a tendency to spring leaks. These can come at any time and at any seal. I bought two of these pads at a Co-op garage sale. They were returned because they leaked. Since I’m pretty good at gear repair, I purchased them, found the leaks (all on the heat welds), and patched them with tent seam seal (very effective). 

I made sure to test the pads by throwing them on top of my own bed and sleeping on them each for two nights. They held air perfectly. I brought the pad on an overnighter and it performed perfectly. On my last campout however, I pitched my tent on a gravel sandbar, inflated my pad, threw my sleeping bag on top and went to bed. I woke up after several hours. Even though it was cool that night, I was so hot that I unzipped the entire length of my sleeping bag. Later that night, I awoke to discomfort; my pad was nearly completely deflated. I re-inflated the pad again and within an hour, I was on the ground again.
Although sleeping on cold gravel on the shores of Lake Superior is uncomfortable, I couldn’t help but think how lucky I was that this didn’t happen in winter. That would have the potential to be life-threatening if the temps were at the lower EN for this pad (at R-value 5.2, the pad is rated down to -1°F (-18°C). 

I brought the pad home and found that the leak was on another heat welded seam like the last two. 
In this picture, you can see the welds that I patched. So far, there have been four distinct leaks on three different occasions. I patched them and also examined the surrounding seams. I identified which ones looked like the weld wasn't perfect and started patching those as well. 

Oddly, if you look at the reviews for this pad as well as the three-season Flash, there are a significant number of reviews that claim leaking at the welds and yet when reviewers have inquired about this manufacturing defect, REI’s response is “We have not received a significant amount a feedback regarding this pad leaking.” From the review chart on their own website, you can see that the feedback about the leak is quite significant. There are more 1-star reviews because of reported manufacturing leaks than any other category. When I went to the Co-op garage sale, the bin was filled with “Flashes”. All “reason for return” tags reported leaking. 

When the pad performs as it should, it’s a top notch item. Comfort, weight, warmth, packability, are all excellent. If the three-season version of the pad leaks, the result is not so grave. If you are going to rely on the pad to perform during winter, the significant risk of deflation makes this pad much too dangerous of an option in my opinion. I’m not sure if REI will be able to mitigate the problem in the future? I hope so. If they do, the Flash All Season Pad would be hard to beat. Until then, make sure you have a backup pad if you bring this into the wilderness.

The campout where I woke up to a full pad. A beautiful morning! I'm trying to end this review on a positive note.

Update3/28/20: I have since filled in each and every weld with seam seal in order to stop the leaks. I finally got the leaks to stop after 5 repairs. I was in heaven for 2 nights and then this happened. 

I think that this pad finally bested me. I don't know if I can trouble shoot this mishap and since I bought it at the REI garage sale, I have no recourse to return, exchange, or otherwise. The adventure continues. 

Background

I've use the pad at home (slept on it for several nights and I lay on it while reading) for a few weeks. I've been on two campouts with this particular model. I keep troubleshooting it and making repairs in preparation for winter, but I'm losing confidence as I go.

I've had trouble with the 3 season version of this pad as well.