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Sea to Summit Spark SP III vs Therm-a-Rest Hyperion 20F/-6C (Regular)

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

Therm-a-Rest Hyperion 20F/-6C (Regular) is the lighter option — 142 g lighter than the Sea to Summit Spark SP III (20% less weight). If grams matter to you, that is the one to beat.
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Spec Sea to Summit Spark SP III Therm-a-Rest Hyperion 20F/-6C (Regular)
Weight 709 g · 0.709 kg · 1.56 lb 567 g · 0.567 kg · 1.25 lb
Brand Sea to Summit Therm-a-Rest
Category Sleep System Sleep System
Sea to Summit Spark SP III
709 g

850-fill down sleeping bag rated to 0°C / 32°F.

Full details →
Therm-a-Rest Hyperion 20F/-6C (Regular)
567 g

Ultralight 20F down mummy bag with 900-fill Nikwax Hydrophobic Down for fast-and-light backpacking.

Full details →

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Sea to Summit Spark SP III vs Therm-a-Rest Hyperion 20F/-6C (Regular): which should you buy?

If saving weight is your priority, the Therm-a-Rest Hyperion 20F/-6C (Regular) wins — at 567 g it is 142 g (20%) 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.

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