Built to be the only bag you need from -20°F to 40°F, Nemo has updated their Backpacker Editors’ Choice award-winning big-mountain bag, Sonic, for even greater warmth, tuneability, and reduced environmental impact. With this bag, they are launching their next-generation Thermo Gills with a new multistage zipper system that dramatically increases the usable temperature range of the bag and allows fine-tuning of comfort from within the bag. Sonic’s new chevron baffle construction better compartmentalizes down, eliminating migration and keeping the down evenly lofted. Not to mention, it looks awesome. In updating the bag's design, they put a high priority on taking a leap forward in sustainability. The shell and liner fabrics are 100% Global Recycled Standard (GRS) certified and bluesign approved. The premium 800 FP hydrophobic down is 100% Responsible Down Standard (RDS) certified. They've also took years of history in the field to make detailed upgrades, including massaging the profile of the bag, redesigning the draft collar, and bolstering the draft tubes. Their proven Toester footbox keeps feet warmer, provides a waterproof barrier against tent wall condensation, and protects down from moisture while drying damp clothes inside the footbox. Adaptable to whatever the mountain throws at it, Sonic continues to reverberate as the ultimate extreme weather companion.