Two sleeping bags worth lining up side by side. Both are solid; the right one depends on the specs you care about most.
| Feathered Friends Hummingbird YF 20 | Sea to Summit Spark 15F | |
|---|---|---|
| GearScore | 87✓ | 67 |
| Comfort rating | 30 °F | 29 °F✓ |
| Weight | 26.1 oz | 25.7 oz✓ |
| Warmth-to-weight | 5.4 /100g | 5.6 /100g✓ |
| Packed size | 9.0 L | n/s |
| Fill power | 900 FP✓ | 850 FP |
| Price | $569 | $549✓ |
| Fill | Down | Down |
| Style | Bag | Bag |
| Shape | Mummy | Mummy |
Highlighted cells mark the better spec: Hummingbird YF 20 in blue, Spark 15F in amber. A blank spec is never counted as a win. A lower comfort rating in °F means a warmer bag, so the warmer bag takes that row. GearScore is the overall rating (0 to 100); re-weight it on the full bag comparison. Prices are current MSRP.
The Feathered Friends Hummingbird YF 20 and Sea to Summit Spark 15F take different routes to the same job. The Hummingbird YF 20 wins on fill power, and the Spark 15F pushes back on warmth and low weight.
The Hummingbird YF 20 is higher fill power (900 vs 850). The Spark 15F is warmer (rated 29°F vs 30°F), 1 oz lighter, and stronger on warmth-to-weight. On the default GearScore the Hummingbird YF 20 leads 87 to 67.
Pick the Hummingbird YF 20 if you care most about fill power, which makes it the better call for your priorities. Pick the Spark 15F if warmth and low weight matter more to you, or you are focused on colder nights and shoulder-season trips.
The Sea to Summit Spark 15F. It is warmer (rated 29°F vs 30°F) than the Hummingbird YF 20.
The Sea to Summit Spark 15F. It is 1 oz lighter than the Hummingbird YF 20.
The Feathered Friends Hummingbird YF 20, 87 to 67 on the default algorithm. You can re-weight the factors to match your trip.
It depends on your priorities. Go with the Hummingbird YF 20 for fill power, or the Spark 15F for warmth. The spec table above shows exactly where each wins.