Thermal compression tops are made from a fabric specifically developed by SKINS which is a blend of hollow core fibres and Spandex. This provides superior hand feel and comfort. The hollow core fibres work in a similar way to polar bear fur by trapping heat and releasing it back to your body to keep you warm. Hollow core fibres are lighter so you wont be weighed down by heavy fabric. Spandex ensures excellent stretch and recovery giving movement without restriction. No polar bears were harmed in the development of this garment.