EXPED's roomiest mummy bag, Comfort is available in three different temperature ratings: Comfort 0, Comfort -4 and Comfort -10 (temp designations are in centigrade). 

Comfort is designed to address the main concern people have with mummy bags - a fit that's too snug. So the cut of this bag is wider and it's higher in volume throughout. Here's a new video outlining the features and benefits: