LOVABLE ODDBALLWith a slide-in pad replacing ground-side stuffing, the Crystal is one strange bird. But it's also hosted some of the deepest slumbers of my life. Coziness arrives courtesy of an insulation-layering scheme called Dualmax, which intersperses slabs of Primaloft with batts of 650-fill down. As I flipped in sleep like a beached fish, the locked-in pad stopped the bag from turning tourniquet. And though loft wasn't huge, the two-pound-ten-ounce, 30-degree bag warmed on autumn nights that flirted with freezing.Bonus: Stuff clothes in the hood's nylon pocket for a ready-made pillow.Bummer: It's not for fetal sleepers.