Prone to cold toes? The Sonora comes in a gender-specific women's model that has extra insulation in the feet and chest, and is roomier around the hips; all versions have a pocket in the footbox to hold heat packs. During a week in the Sierra, our cold-sleeping tester stayed plenty warm when temperatures dipped to freezing, thanks to a generous amount of Polarguard 3D insulation that always lofted up. But any bag worth buying should keep you warm at its promised rating. She called the Sonora "downright plush" for its perfect cut, with just-right wiggle room, and no cold spots when she curled up on her side. The fat draft collar and zipper tube seal in heat. On damp nights, condensation rolled off the nylon ripstop shell.