Side-by-side scoring from our full field testing. Scores are ours, price-checked on publish date. When you buy through our links we may earn a commission.
Quick verdict
Trestles 15 wins if your shoulder seasons are wet or you camp from the trunk – synthetics don’t care about dew and it costs $60 less. Cosmic 20 wins the moment you carry the bag more than a mile: the weight and packed-size savings are the whole point of paying for down.
Marmot Trestles 15 — 37/50 ($119)
| 1. Marmot Trestles 15 — total 37/50 | ||
|---|---|---|
| Warmth | 8/10 | Honest 15-20°F synthetic, tolerant of damp |
| Weight & packed size | 5/10 | Under 3 lbs but bulky when stuffed |
| Comfort | 8/10 | Roomy mummy cut, full-length draft tube |
| Durability | 8/10 | Spatula-shell fabric shrugs off tent floors |
| Value for the money | 8/10 | The one-bag answer for car + shoulder backpacking |
Kelty Cosmic 20 — 37/50 ($180)
| 2. Kelty Cosmic 20 — total 37/50 | ||
|---|---|---|
| Warmth | 8/10 | True 20°F down, warmer per ounce |
| Weight & packed size | 8/10 | Compresses to Nalgene size, 2.4 lbs |
| Comfort | 7/10 | Slightly snug mummy |
| Durability | 7/10 | Lightweight shell needs a pad under it |
| Value for the money | 7/10 | Cheapest credible 650-fill down bag |
Where the Marmot Trestles 15 wins
Trestles takes damp-cold performance, dorm-room durability, and price. It is also warmer than its rating in humid conditions.
Where the Kelty Cosmic 20 wins
Cosmic takes packability, ounces on your back, and loft recovery after compressing all season.
Price math
The gap is $61. At $119 the Marmot Trestles 15 is the tool, at $180 the Kelty Cosmic 20 is the hedge.
Buy
Full methodology and the rest of the field: see our complete buying guide, linked above.