Built to be the only bag you need from -20°F to 40°F, we’ve updated our Backpacker Editors’ Choice award-winning big-mountain bag, Sonic, for even greater warmth, tuneability, and reduced environmental impact. With this bag, we are launching our 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, we put a high priority on taking a leap forward in sustainability. The shell and liner fabrics are 100% recycled fabrics and bluesign® approved. The premium 800 FP hydrophobic down is 100% Responsible Down Standard (RDS) certified. We 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. Our 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 Gills™ extend the comfort range with a new multistage zipper system.
• Overstuffed with premium 800 FP hydrophobic down that is PFC-Free and 100% Responsible Down Standard (RDS) certified, ensuring humane treatment and traceability throughout the supply chain.
• 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.
• Protected by the NEMO Lifetime Warranty.