Sonic is built to be the only bag you need from -20°F to 40°F. The Backpacker Editors' Choice award-winning big-mountain bag offers exceptional warmth and tuneability with a reduced environmental impact. This bag features our next-generation Thermo GillT vents, with a new multistage zipper system that dramatically increases the usable temperature range of the bag and allows fine-tuning of comfort from within. Sonic's chevron baffle construction better compartmentalizes down, eliminating migration and keeping the down evenly lofted.
Adaptable to whatever the mountain throws at it, Sonic continues to reverberate as the ultimate extreme weather companion. Award Winning Design for Warmth Retention and Adjustability of Temperature. T and Multistage Zipper System.
Stretch Construction at Knees for Side Sleepers. Draft Collar and Draft Tubes to Keep Cold Air Out. Fits up to 6'6. Sonic Down Mummy Sleeping Bag.