Winter nights can drag when you’re cooped up in your tent—and in your bag—which is why we love the roomy dimensions of this semi-rectangular sack. “Going from a mummy to this is like swapping a broom closet for an airplane hangar,” says one tester. “I could toss and turn freely, and even change clothes without unzipping the bag.” Credit the 70-inch shoulder circumference and 53-inch footbox (traditional mummies measure 60 and sub-40, respectively). The U-shaped draft collar and puffy draft tube behind the full-length zipper form an impenetrable barrier that seals in heat. While we only tested it down to 15°F, our tall Alaska tester would confidently take this down to single digits, but smaller bodies may have trouble warming up the extra room. The 650-fill duck DownTek keeps the price low for a 0°F bag. Tradeoff: All that extra room equals a bulky (8 by 17 inches) package.