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 design is updated for even greater warmth retention and adjustability across temperatures.
• Updated design incorporates 100% recycled, bluesign®-approved shell and liner fabrics.
• Updated Thermo Gill™ vents extend the comfort range with a new multistage zipper system.
• Overstuffed with premium 800 FP hydrophobic down that 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 construction at the knees for comfortable side sleeping.
• Redesigned draft collar and draft tubes keep cold air out.
• Redesigned Toester™ waterproof/breathable footbox utilizes a layer of synthetic insulation to protect the down and deliver maximum toastiness for toes.
• Offset zipper creates a thermally efficient seal while an updated profile secures warmth closer to the body.