Here is how these two sleeping pads compare on the numbers. They score within a hair of each other, so it comes down to the details below.
| Sea to Summit Ultralight XR Insulated | REI Co-op Flash Insulated Air | |
|---|---|---|
| GearScore | 84✓ | 83 |
| Warmth (R-value) | 3.6 R | 3.7 R✓ |
| Weight | 13.8 oz✓ | 15.0 oz |
| Warmth-to-weight | 0.92 R/100g✓ | 0.87 R/100g |
| Packed size | 1.46 L✓ | 1.97 L |
| Thickness | 2.6 in✓ | 2.0 in |
| Durability | 39 /100✓ | 30 /100 |
| Price | $149 | $99.95✓ |
| Features | 3Pump sack included, Two-way valve, Repair kit included✓ | 1Two-way valve |
| Type | Inflatable | Inflatable |
| Shape | Tapered | Mummy |
Highlighted cells mark the better spec: Ultralight XR Insulated in blue, Flash Insulated Air in amber. A blank spec is never counted as a win. GearScore is the rating for the Overall use-case (0 to 100). Pick another above to re-score. Prices are current MSRP.
The Sea to Summit Ultralight XR Insulated against the REI Co-op Flash Insulated Air is a study in priorities. They are close enough that this really is about which handful of specs you weight most.
The Ultralight XR Insulated is 1 oz lighter, stronger on warmth-to-weight, and more packable (1.5 L vs 2 L). The Flash Insulated Air is warmer (R 3.7 vs R 3.6) and $49 cheaper. Their GearScores land within a couple of points (84 vs 83), so neither runs away with it.
Pick the Ultralight XR Insulated if you care most about low weight and warmth-to-weight, which makes it the better call for counting grams on long miles. Pick the Flash Insulated Air if warmth and price matter more to you, or you are focused on colder nights and shoulder-season trips.
The Sea to Summit Ultralight XR Insulated. It is 1 oz lighter than the Flash Insulated Air.
The REI Co-op Flash Insulated Air. It is warmer (R 3.7 vs R 3.6) than the Ultralight XR Insulated.
They are nearly tied at 84 and 83 on the default algorithm, so re-weight the score to your own priorities to break the tie.
It depends on your priorities. Go with the Ultralight XR Insulated for low weight, or the Flash Insulated Air for warmth. The spec table above shows exactly where each wins.