You go out when others come in? Get this heater. Camping under the stars in Alaska’s Kenai Fjords National Park, one cold-sleeping tester stayed warm—even hot—in subzero temperatures. The Expedition starts with clouds of 700-fill down and a waterproof/breathable shell—but other bags can make similar claims. What sets this sack apart are several innovations. The muffler around the perimeter of the face opening is overstuffed, and when cinched, it formed a tighter-than-average seal around our faces.
The fluffy draft yoke is slightly underfilled, which allowed it to drape naturally around testers’ necks. The unique double, offset zipper system—one zip is attached to the shell, the other to the liner—creates the same thermal efficiency as a puffy draft tube, but with this benefit: The zippers adjust internal volume. On warmer nights, just leave the inner zip open for more thrashing room. “It’s a very effective system, and despite the extra materials, the overall weight is still low for a bag this warm,” says one tester.
The tradeoff: Getting in and out of the double zippers is slow at first. Size-wise, the thermally efficient cut is ideal for smaller folks. “It was snug enough that it was easy to heat up, but I could still change my socks in the bag,” says our 5’, 125-pound female tester. But our 5’11”, 175-pound guy found it tight. $399; 3 lbs. 10 oz.; -20°F