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Sea to Summit Ultralight XR Insulated (Short) vs Therm-a-Rest Vesper 20 Sleeping Bag

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

Sea to Summit Ultralight XR Insulated (Short) is the lighter option — 160 g lighter than the Therm-a-Rest Vesper 20 Sleeping Bag (29% less weight). If grams matter to you, that is the one to beat.
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Spec Sea to Summit Ultralight XR Insulated (Short) Therm-a-Rest Vesper 20 Sleeping Bag
Weight 390 g · 0.390 kg · 0.86 lb 550 g · 0.550 kg · 1.21 lb
Brand Sea to Summit Therm-a-Rest
Category Sleep System Sleep System
Sea to Summit Ultralight XR Insulated (Short)
390 g

Ultralight insulated sleeping pad at 13.8 oz (390g) for 66-inch length with 3.6 R-value, lightest inflatable option available.

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Therm-a-Rest Vesper 20 Sleeping Bag
550 g

900-fill hydrophobic goose down sleeping bag rated to 20°F/-6°C. Ultralight and highly compressible for three-season backpacking.

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Sea to Summit Ultralight XR Insulated (Short) vs Therm-a-Rest Vesper 20 Sleeping Bag: which should you buy?

If saving weight is your priority, the Sea to Summit Ultralight XR Insulated (Short) wins — at 390 g it is 160 g (29%) lighter than the Therm-a-Rest Vesper 20 Sleeping Bag (550 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.

More sleep system comparisons