The most room and ventilation options of any down bag available; 5 FIdeal for adventures with a base camp, the Sea to Summit Amplitude AmIII Double down sleeping bag brings spacious luxury and incredibly versatile ventilation options to wherever your travels may take you. Each side of the Amplitude has a full-length side zipper; a third zipper can be found in the foot box. High-lofting down and quality construction keeps you cozy when its cold, and the zippers provide temperature regulation up to the point where you remove the upper section and sleep under it as a quilt. The down is responsibly sourced and RDS certified and treated with the environmentally-friendly Ultra-Dry Down treatment.