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Sea to Summit Spark Pro Down Sleeping Bag vs Western Mountaineering MegaLite 35°F

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

Western Mountaineering MegaLite 35°F is the lighter option — 255 g lighter than the Sea to Summit Spark Pro Down Sleeping Bag (33% less weight). If grams matter to you, that is the one to beat.
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Spec Sea to Summit Spark Pro Down Sleeping Bag Western Mountaineering MegaLite 35°F
Weight 765 g · 0.765 kg · 1.69 lb 510 g · 0.510 kg · 1.12 lb
Brand Sea to Summit Western Mountaineering
Category Sleep System Sleep System
Sea to Summit Spark Pro Down Sleeping Bag
765 g

Ultralight down sleeping bag at 765g with 900+ fillpower RDS-certified down, 15°F rating and Free-Flow Zip system for versatility.

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Western Mountaineering MegaLite 35°F
510 g

Ultralight 850-fill down bag for warm summer conditions.

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Sea to Summit Spark Pro Down Sleeping Bag vs Western Mountaineering MegaLite 35°F: which should you buy?

If saving weight is your priority, the Western Mountaineering MegaLite 35°F wins — at 510 g it is 255 g (33%) lighter than the Sea to Summit Spark Pro Down Sleeping Bag (765 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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