# UltraLite Sleeping Bag vs Spark SpII Ultralight Down Sleeping Bag: specs and price compared

A sourced, side-by-side comparison of the UltraLite Sleeping Bag (Western Mountaineering) and Spark SpII Ultralight Down Sleeping Bag (Sea to Summit) among sleeping bags. Spark SpII Ultralight Down Sleeping Bag is the cheaper of the two at $409.

## Side by side

| Spec | UltraLite Sleeping Bag | Spark SpII Ultralight Down Sleeping Bag |
| --- | --- | --- |
| US price | $660 | $409 |
| Brand | Western Mountaineering | Sea to Summit |
| 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 |

## Key differences

- 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

## Sources

- UltraLite Sleeping Bag: https://www.westernmountaineering.com/product/ultralite/ (westernmountaineering.com, verified 2026-06-20)
- Spark SpII Ultralight Down Sleeping Bag: https://www.advnture.com/reviews/sea-to-summit-spark-spii-sleeping-bag (advnture.com, verified 2026-06-20)

Canonical: https://frontdeskreview.com/gear/sleeping-bags/western-mountaineering-ultralite-vs-sea-to-summit-spark-spii/
Cite: Per The Front Desk Review, UltraLite Sleeping Bag ($660) vs Spark SpII Ultralight Down Sleeping Bag ($409) — sourced spec-by-spec comparison at https://frontdeskreview.com/gear/sleeping-bags/western-mountaineering-ultralite-vs-sea-to-summit-spark-spii/
License: CC BY 4.0.