The North Face Men's Inferno 0F/-18C

The North Face says:

A dependable workhorse for zero-degree expeditions, this down bag is thirsty for cold-weather. Constructed with 850 fill goose down, this lofty down Summit Series® bag is designed with bomber, waterproof Pertex Endurance shell to prevent you from getting, or staying, wet in critically cold conditions. Most down bags lose their warmth when wet – this bag eliminates that.