Which is the better buy? Side-by-side on rating, price, strengths, and watch-outs — with the published ratings we averaged to get there.
Sea to Summit Spark 0 comes out ahead by a narrow margin (4.7 vs 4.6). The gap is mostly about ultralight backpackers prioritizing pack weight — read the strengths below before deciding.
The Spark 0 is the best-overall pick — Sea to Summit's lightweight zero-degree bag with 850 fill.
The Parsec 0 is the fast-and-light pick — Therm-a-Rest's lightest zero-degree bag for speed missions.
Best warmth-to-weight. Lightest shell. Premium.
Lightest pick. Less warm than Kodiak MF. Toe Box.
| Spec | Sea to Summit Spark 0 | Therm-a-Rest Parsec 0 |
|---|---|---|
| Fill | 850 fp down | 800 fp down |
| Shell | 10d nylon | — |
| Weight | Ultralight | Lightest 0° |
| Brand | Sea to Summit | Therm-a-Rest |
| Features | — | Toe Box |