Waterproof Body 2X Double Layer Top- Women'sWhen designing the BODY X and BODY 2X, we were inspired by the structure of the fur of a polar bear living under extreme environmental conditions. BODY X and BODY 2X are made of a hollow fiber polyester fleece. It insulates far better than a regular fiber due to being hollow and filled with air. It is a material that achieves high thermal insulation without increasing weight. Its all about keeping warm and dry! This technically advanced fabric also