3M THINSULATE Isulation: extra warm thanks to this proven lining! Thinsulate Insulation is a microfiber fabric developed by 3M that scores above all with its good insulation performance. Depending on the material variant, Thinsulate Insulation is made of polyester or a mixture of polyester and polypropylene. The tight structure reduces the heat flow between the individual fibers. This allows body heat to be reflected back from the fibers and the material keeps you warm even at low temperatures. In addition, the material is breathable and moisture-repellent.