Combat the cold with nasa thermal sweatshirts theyre a winter wardrobe essentialreflects heat back to bodyinterwoven with conductive metallic threadsribbed crew neck and cuffsshortcode tabdescriptionmaximum warmth total comfort relaxed style three excellent reasons why these thermal sweatshirts are selling like hot cakes similar in design to the clothing developed by nasa for astronauts theyre made from a special blend of polyester polyamide and cotton interwoven with conductive meta