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Sea to Summit Spark Pro Down 30 vs Sea to Summit Spark SP I

Weight and specs compared for 2026 — and which one to choose.

Sea to Summit Spark SP I is the lighter option — 222 g lighter than the Sea to Summit Spark Pro Down 30 (36% less weight). If grams matter to you, that is the one to beat.
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Spec Sea to Summit Spark Pro Down 30 Sea to Summit Spark SP I
Weight 619 g · 0.619 kg · 1.36 lb 397 g · 0.397 kg · 0.88 lb
Brand Sea to Summit Sea to Summit
Category Sleep System Sleep System
Sea to Summit Spark Pro Down 30
619 g

Ultralight mummy bag rated to 30F (-1C) with 950+ fill-power Ultra-Dry Down. 10-denier shell, shoulder and footbox zippers for temperature control.

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Sea to Summit Spark SP I
397 g

Ultralight 850-fill down sleeping bag rated to 25°C.

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Sea to Summit Spark Pro Down 30 vs Sea to Summit Spark SP I: which should you buy?

If saving weight is your priority, the Sea to Summit Spark SP I wins — at 397 g it is 222 g (36%) lighter than the Sea to Summit Spark Pro Down 30 (619 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.

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