This Backpacker Editors’ Choice award-winning big-mountain bag offers exceptional warmth and tuneability with a reduced environmental impact. The Sonic -20 features NEMO's next-generation Thermo Gill 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. (Not to mention, it looks awesome.)

The shell and liner fabrics are 100% recycled fabrics and bluesign-approved, and the premium 800 FP hydrophobic down is 100% Responsible Down Standard (RDS) certified. Years of history in the field yielded detailed upgrades on this bag, including a perfected profile, redesigned draft collar, and bolstered draft tubes. Its 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.

• Award-winning designis updated for even greater warmth retention and adjustability across temperatures.
• Updated design incorporates 100% recycled, bluesign-approved shell and liner fabrics.
• UpdatedThermo Gill ventsextend the comfort range with a new multistage zipper system.
• Overstuffed withpremium 800 FP hydrophobic downthat is PFAS-free and 100%RDS-certified. Products certified to the Responsible Down Standard (RDS) contain down or feathers from farms certified to animal welfare requirements.
• New chevron baffle construction better compartmentalizes down for more uniform loft and down migration prevention.
• Stretch constructionat the knees for comfortable side sleeping.
• Redesigned draft collaranddraft tubes keep cold air out.
• RedesignedToester waterproof/breathable footboxutilizes a layer of synthetic insulation to protect the down and deliver maximum toastiness for toes.
• Offset zippercreates a thermally efficient seal while an updated profilesecures warmth closer to the body.