Marmot Atom

Go light without sacrificing warmth with the Marmot Plasma 0.

Brand: Marmot Gear Reviews

Model: Atom

[editors ’ choice update]

Minimum weight, maximum warmth. That’s the Plasma’s guiding philosophy, and testers approve. The 15°F version won our Editors’ Choice Award in 2011 for its standout warmth-to-weight ratio, and this new model extends the award-winning range. “I was toasty warm on a 10°F night at 11,000 feet in Wyoming’s Tetons,” says a tester. “It could easily go 10 degrees colder.” Credit a cloud of 900-fill goose down and vertical baffles, which help it warm up in a flash and eliminate cold spots.

No matter which way our tester slept—on her side, back, or belly—the Plasma proved consistently cozy. The draft collar cinches to seal out icy air, and the 10-denier Pertex Quantum fabric proved surprisingly water-repellent: When a leaky hydration bladder doused the bag, the DWR coating kept water from penetrating. Yet the Plasma is also outstandingly breathable, so that in all temperatures (even a balmy 30°F) our tester never felt clammy. The superpuffy hood uses no Velcro, so there’s nothing to scratch cold skin. Like the 2011 award-winning Plasma 15, this version is designed for efficiency—the 60-inch shoulder girth doesn’t accommodate broad-shouldered guys, and the sharp taper means there’s not enough room to pull your knees up inside. It’s not for claustrophobes. Or penny pinchers. $649; 2 lbs. 7 oz.; 0°F;

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