During a normal night, a person releases up to 500g of sweat in the form of water vapor. This moisture - should it remain in the insulation layer of the sleeping bag - leads to a drastic decrease in the insulation performance. At very low temperatures, the dew point (the temperature at which water vapor becomes liquid) is usually on the inside of the outer shell. In extreme cold, this condensation can even freeze to ice, which means that the filling cannot dry in the long term and the sleeping bag becomes heavier and wetter. This leads to a drastic drop in the insulation performance of the down sleeping bag.
This system uses a second inverted outer shell made of water-repellent and breathable Shellproof Ultra. With a corresponding zip opening, this layer can simply be turned outwards to dry. Ice crystals or drops of water that have formed between the layers can be easily shaken off. In order to dry the remaining condensation moisture more quickly, the inner sleeping bag cover is made of down-proof but extremely breathable Shelltex Ultra.
The additional air layer between the outer shells increases the heat storage capacity and thus achieves a sensational warmth-to-weight ratio.