Vapor barrier liner liner gives about 10 F. You wake up damp and they are not real comfortable but they work. Not only does it hold some heat in it prevents moisture from building up in the bag. Especially over multiple cold nights a bag will build up condensation. A buddy of mine used one year round for ultralight.

Vapor barrier liner gives about 10 F. You wake up damp and they are not real comfortable but they work. Not only does it hold some heat in it prevents moisture from building up in the bag. Especially over multiple cold nights a bag will build up condensation. A buddy of mine used one year round for ultralight.

I don't even know where to find them anymore but an airtight liner gives about 10 F. You wake up damp and they are not real comfortable but they work. Works better for summer ultralight where you can get up and dry out before getting too cold.

Vapor barrier liner liner gives about 10 F. You wake up damp and they are not real comfortable but they work. Not only does it hold some heat in it prevents moisture from building up in the bag. Especially over multiple cold nights a bag will build up condensation. A buddy of mine used one year round for ultralight.