Our take Hikers who have cut every gram of fat from their kits will drool over this ultralight sack from Marmot. At a feather under a pound and a half, it’s in a rarefied weight class for a legit three-season bag. The recipe—premium materials and a trim cut—has been used before, but rarely to such effect. Both the shell and liner are made with 10-denier Pertex Quantum, making it easy for the 850-fill goose down to loft to full height (even after the bag sits in a compression sack for multiple travel days). Check fit: The efficient cut uses less material than a traditional mummy, but it also makes for one of the tightest bags we tested.
The details A two-way, full-length zip (a rarity in ultralight bags) makes venting easy on warm nights, the interior pocket secures small items like camera batteries, and the roomy hood accommodates a backpacking pillow.
Trail cred “I packed this while trekking across Australia and New Zealand,” says a tester. “I could easily fit everything I needed for a three-day backcountry trip into a 36-liter pack, since this packs down to 7.5 by 16 inches—even smaller with a compression sack (not included).”