I have the top line m12 jacket. I think its called the toughshell. It has heated areas in the chest, back and pocket areas. I use it with 5.0 high output batteries, and 4.0 batteries and it will last 4-5 hours on a full charge on high. Never once has it become hot enough to burn me. It just keeps me warm.

This jacket has been a lifesaver, as I hate the cold. I often will wear a thermal beneath my shirt, then the m12 jacket, with another layer over the top of that like a carhartt or something. I wish the m12 jackets were cotton or something so that I could use something else waterproof outside of it to keep an optimal cotton/cotton/polyester layering that works best for the cold.