What’s the quilt structure of your sleeping bag? Is that fit well for the purpose? Does your supplier told you which structure is used for your sleeping bag and feature of each structure? Normally, there are 2 different structures on the market, the H chamber and double H chamber.
The H Chamber is simplest and most popular structure, sew the shell, insulation and lining together directly. This structure is usually used for summer-spring models.
Double H chamber, which is most popular used for low temperature sleeping bag. There are 2 separate layers, the outer layer sew shell & one layer of insulation together and the inner layer sew lining and another layer of insulation together, then sew 2 layers together. This double H structure could have more insulation and better performance than H chamber to keep sleeping bag warmer. After lots of thermal insulation test with “thermal dummy”, we find there’s still "Cold Points", so we apply an improved double H structure.
Improved double H chamber, as it’s name shows, it’s improved based on double H chamber. The quilt line on double H for both 2 layers are at same level, thermal will loss through these “cold pints”. In order to solve this problem, we designed this improved double H chamber.