Which is warmer, the Kelty Cosmic 20 or the Marmot Trestles 30?

The Kelty Cosmic 20. Its 20°F rating is 10 degrees lower than the Marmot's 30°F, and its down fill gives more warmth per ounce.

Which bag is better for wet climates?

The Marmot Trestles 30. Its synthetic SpiraFil fill keeps loft when damp, while the Kelty's down loses insulation once wet.

Is the Kelty worth the extra money?

Yes for cold-weather backpackers. At $179.94 versus $118.95 as of November 6, 2026, you pay about $61 more for a warmer bag that weighs roughly 9 oz less and packs smaller.

Which is better for mild summer camping?

The Marmot Trestles 30. A 30°F synthetic bag is enough for mild nights and costs less, and the weight penalty matters less on short trips.

Down generally holds loft longer than synthetic fill if kept dry and stored uncompressed. The Marmot's synthetic fill degrades faster with repeated compression.

Do both come with a stuff sack?

Yes. The Kelty includes an 8 x 14 in stuff sack, and the Marmot includes a compression stuff sack.

Kelty Cosmic 20 Down Sleeping Bag vs Marmot Trestles 30 Sleeping Bag

Buy the Kelty Cosmic 20 if you sleep cold or camp in shoulder-season and winter conditions; its 20°F rating and 550-fill down pack smaller and weigh less. Buy the Marmot Trestles 30 if you want a budget synthetic bag for mild nights and don't mind the extra weight. The Kelty is $179.94 at Amazon as of November 6, 2026, and the Marmot is $118.95 at Backcountry.com as of the same date, a gap of about $61.

Today the Marmot Trestles 30 Sleeping Bag costs $60.99 less at its best price.

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