Nunatak Sastrugi Sleeping Bag (22°F) vs Sea to Summit Spark SP III
Weight and specs compared for 2026 — and which one to choose.
Custom ultralight sleeping bag with 900-fill goose down. 614g for 22-degree regular-width medium-length configuration. Made to order with customization options
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Nunatak Sastrugi Sleeping Bag (22°F) vs Sea to Summit Spark SP III: which should you buy?
If saving weight is your priority, the Nunatak Sastrugi Sleeping Bag (22°F) wins — at 614 g it is 95 g (13%) lighter than the Sea to Summit Spark SP III (709 g). That said, the heavier option may justify the extra grams with more capacity, durability or comfort, so weigh the trade-off against how you'll use it.
See where both rank against everything else in this category on the lightest sleep system page, or browse the full gear weight database.