Most quality mummy bags feature hood and neck closure with a drawstring that pulls the hood snug to your head. Also look for a self-repairing coil zipper and a zipper baffle which is an insulated flap that covers the zipper on the inside to help keep the warm air in, cold air out. And if you're buying bags for more than one person, consider styles that let you zip two mummy bags together with left and right-hand zippers. Tapered with Barrel-style bags are modified mummy shapes but with more room for the shoulders, hips and feet than the typical mummy, offering a little more room to stretch while still being light in weight. If you're really looking for room above all else, go rectangular, but you might be trading off lighter weight and some compressibility to get it.
Oversized bags can be wider and longer.
Like many mummies, most rectangular bags also zip together to effect a sleeping bag built for two. In Your Head To Sleep On Rocks For A Bed. Not only would it turn a sleeping night mare into a dream by providing cushion between you, the hard earth, and ever lurking rocks, a pad will insulate you against the cold, heat robbing ground. The Difference Is In The Details. You can make two different bags out of the same material and one would be warmer just by how it was designed and constructed.