BEST FOR: When weight is everything.
THE TEST: With most sleeping bags, ultralight means ultratight. Yet even though Sierra Designs kept features to a minimum—a half-length, one-way zip and a tissue-thin nylon shell and liner—whittling this water-resistant, 800-fill down bag to under two pounds, the standard size still fit a 200-pound six-footer with room to wiggle. “Usually, I’m uncomfortable in a standard, but I slept like a baby,” he said. Another plus: the jacket-style hood can be cinched down to form a snug pocket of warmth.
THE VERDICT: The half-length zip isn’t as comfortable or ventable as a full-length one, but most testers didn’t care, as the Cal is the lightest and warmest bag here—and packs down smaller than some puffy jackets. 13˚; 1.7 lbs.
WARMTH-TO-WEIGHT RATIO: 5