[high loft, low weight]
Like other high-end down sacks, the Cal is puffy, packable, and cozy. But it’s also filled with water-repellent 800-fill DriDown, which Sierra Designs says stays drier 10 times longer and retains 170 percent more loft than untreated down (see Gear Glossary, page 87). During a December trip to 8,700 feet in Idaho’s Pioneer Mountains, an iced-up bivy soaked parts of the bag, including the draft collar—but the Cal never lost a hint of loft.
Vertical baffles channel heat throughout the bag and help it warm up fast. “I really felt the difference,” says one tester, who hardly noticed the few moments of chill before his body heat warmed the bag. He also vouches for the bag’s rating. “I stayed warm during a bivouac in temps nearing zero,” he says. The highly compressible down lets this bag shrink to soccer-ball size when packed. The cut is roomy, with a generous 62-inch girth at the shoulders and a length that perfectly fit one 5’11” sleeper. Of course, ultralight warmth like this ain’t cheap. $500; 1 lb. 12 oz.; 13°F; sierradesigns.com