Nemo Sonic Sleeping Bag

The Nemo Sonic is rated for 0°F, which is its ISO Limit rating. The ISO Comfort rating is 14°F, meaning most sleepers will be comfortable down to that temperature before needing to adjust their layering or sleep system.

Thermo Gill vents are essentially zippered slits on the top of the bag that allow you to dump excess heat without unzipping the main zipper. This lets you regulate your temperature during the night without letting cold air rush into the entire bag.

No, the Sonic uses a chevron baffle construction specifically designed to prevent down migration. This keeps the insulation evenly distributed across your body so you don't end up with thin spots.

While it features a mummy shape for maximum heat retention, it is designed with a refined profile that balances warmth with enough room for comfortable movement. If you are a very active sleeper, you may find it slightly more restrictive than a rectangular bag, but it offers more room than traditional tight-fitting mummy bags.

The Toester footbox is a specialized section at the bottom of the bag designed to provide extra warmth for your feet. It helps prevent the common issue of cold toes, which is often the first place you feel the chill in freezing conditions.

The shell is made from 20D recycled nylon, but it is not waterproof. While it can handle light condensation inside a tent, you should use a bivy or ensure your tent setup is reliable if you are expecting heavy moisture.