Sea to Summit Spark SP I vs Therm-a-Rest Z Lite Sol

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

Sea to Summit Spark SP I is the lighter option — 13 g lighter than the Therm-a-Rest Z Lite Sol (3% less weight). If grams matter to you, that is the one to beat.

Spec	Sea to Summit Spark SP I	Therm-a-Rest Z Lite Sol
Weight	397 g · 0.397 kg · 0.88 lb	410 g · 0.410 kg · 0.90 lb
Brand	Sea to Summit	Therm-a-Rest
Category	Sleep System	Sleep System

Sea to Summit Spark SP I

397 g

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

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Therm-a-Rest Z Lite Sol

410 g

Classic accordion-fold foam pad. R-value 2.0. Indestructible.

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Sea to Summit Spark SP I vs Therm-a-Rest Z Lite Sol: which should you buy?

If saving weight is your priority, the Sea to Summit Spark SP I wins — at 397 g it is 13 g (3%) lighter than the Therm-a-Rest Z Lite Sol (410 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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