Western Mountaineering
UltraLite Sleeping Bag
$660
Best Sleeping Bags · head-to-head
UltraLite Sleeping Bag vs Spark SpII Ultralight Down Sleeping Bag
A sourced, side-by-side comparison. Spark SpII Ultralight Down Sleeping Bag is cheaper at $409. Every spec and price links to its source.
Sea to Summit
Spark SpII Ultralight Down Sleeping Bag
$409Cheaper
Which is better: the UltraLite Sleeping Bag or Spark SpII Ultralight Down Sleeping Bag?
The Spark SpII Ultralight Down Sleeping Bag wins 1 of the 1 specs we compare head to head; the other wins 0. The Spark SpII Ultralight Down Sleeping Bag is the cheaper at $409. The Spark SpII Ultralight Down Sleeping Bag both leads on specs and costs less — the straightforward pick.
As an Amazon Associate we earn from qualifying purchases. Prices verified at capture; live price may differ.
Full spec sheet
✓ marks the stronger figure where "more" — or "less", for price and weight — is unambiguously better.
| Spec | UltraLite Sleeping Bag | Spark SpII Ultralight Down Sleeping Bag |
|---|---|---|
| US price | $660 | $409 |
| Brand | Western Mountaineering | Sea to Summit |
| Released | — | — |
| Temperature rating f | 20 | 28 |
| Insulation type | down | down |
| Fill power | 850 | 850 |
| Shape | mummy | mummy |
| Packed weight (lb) | 1.81 | 1.17 |
| Packed size | 7 x 13 in | 2.5 L (approx. 1-liter bottle size) |
| Zipper side | left or right | — |
| Product note | 850+ FP ethically-sourced premium goose down; USA made; full-length #5 YKK zipper; 6'0" version weighs 1 lb 13 oz | Lower limit 28F / -2C; comfort 38F / 4C; Ultra-Dry Down PFAS-free treatment; regular size; 530 g / 18.7 oz |
Sources — UltraLite Sleeping Bag: westernmountaineering.com (verified 2026-06-20). Spark SpII Ultralight Down Sleeping Bag: advnture.com (verified 2026-06-20).
What's the difference between the UltraLite Sleeping Bag and Spark SpII Ultralight Down Sleeping Bag?
Where the two actually differ on the specs we track (4 of 8). Matching specs are omitted.
- Temperature rating f: UltraLite Sleeping Bag 20 vs Spark SpII Ultralight Down Sleeping Bag 28
- Packed weight (lb): UltraLite Sleeping Bag 1.81 vs Spark SpII Ultralight Down Sleeping Bag 1.17
- Packed size: UltraLite Sleeping Bag 7 x 13 in vs Spark SpII Ultralight Down Sleeping Bag 2.5 L (approx. 1-liter bottle size)
- Product note: UltraLite Sleeping Bag 850+ FP ethically-sourced premium goose down; USA made; full-length #5 YKK zipper; 6'0" version weighs 1 lb 13 oz vs Spark SpII Ultralight Down Sleeping Bag Lower limit 28F / -2C; comfort 38F / 4C; Ultra-Dry Down PFAS-free treatment; regular size; 530 g / 18.7 oz