Here is how these two sleeping pads compare on the numbers. The Helix Insulated leans on low weight while the Stratosphere 5.5 answers with warmth, so the pick comes down to which you value.
| REI Co-op Helix Insulated | Rab Stratosphere 5.5 | |
|---|---|---|
| GearScore | 79✓ | 75 |
| Warmth (R-value) | 4.9 R | 5.5 R✓ |
| Weight | 21.0 oz✓ | 27.7 oz |
| Warmth-to-weight | 0.82 R/100g✓ | 0.70 R/100g |
| Packed size | 3.05 L✓ | 3.19 L |
| Thickness | 3.0 in | 3.1 in✓ |
| Durability | 30 /100 | 70 /100✓ |
| Price | $169 | $150✓ |
| Features | 0 | 2Pump sack included, Repair kit included✓ |
| Type | Inflatable | Inflatable |
| Shape | Mummy | Rectangular |
Highlighted cells mark the better spec: Helix Insulated in blue, Stratosphere 5.5 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 REI Co-op Helix Insulated against the Rab Stratosphere 5.5 is a study in priorities. The Helix Insulated wins on low weight and warmth-to-weight, and the Stratosphere 5.5 pushes back on warmth and cushion.
The Helix Insulated is 7 oz lighter, stronger on warmth-to-weight, and a touch more packable. The Stratosphere 5.5 is warmer (R 5.5 vs R 4.9), thicker for more cushion, and more durable. On the default GearScore the Helix Insulated leads 79 to 75.
Pick the Helix 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 Stratosphere 5.5 if warmth and cushion matter more to you, or you are focused on colder nights and shoulder-season trips.
The REI Co-op Helix Insulated. It is 7 oz lighter than the Stratosphere 5.5.
The Rab Stratosphere 5.5. It is warmer (R 5.5 vs R 4.9) than the Helix Insulated.
The REI Co-op Helix Insulated, 79 to 75 on the default algorithm. You can re-weight the factors to match your trip.
It depends on your priorities. Go with the Helix Insulated for low weight, or the Stratosphere 5.5 for warmth. The spec table above shows exactly where each wins.