The Vapor Barrier is a sleeping bag liner designed to protect your sleeping bag from moisture while also trapping your body heat and keeping you warm and comfortable in the harshest cold weather conditions.
The COCOON Vapor Barrier Liner surrounds your body with an ultralight, 100% non-breathable 15 Denier Ripstop Nylon shell that is laminated with a TPU-film on the inside. Ideal for long winter trips under extremely cold conditions, the technical liner minimizes evaporative heat loss and reduces dehydration. It helps to maintain the insulation and the loft of your sleeping bag by protecting it from body moisture. The Vapor Barrier Liner also makes a great emergency bivy.
Cocoon's Vapor Barrier MummyLiner is a very niche product designed to be used as a sleeping bag liner in the coldest conditions. This non-breathable liner is designed to go inside your sleeping bag in order to create a barrier between you and the down in your bag. It is generously sized and has a drawcord to help trap in a bit more heat when needed. It helps if you look after the bag and clean the inner, waterproof layer as it will last longer too.
Although the bag isn't the most comfortable liner you're going to use it certainly performs well and does exactly what you need it too. In seriously cold winter conditions it has kept my sleeping bag dry which has been ideal on multiday trips where there is little chance to air or dry the bag.
- Reviewed by Ultralight Outdoor Gear