A Cornish Rex is a breed of domestic cat. The Cornish Rex has no hair except for down. Most breeds of cat have three different types of hair in their coats: the outer fur or guard hairs which is about 5 cm long in shorthairs and 10cm+ long in longhairs; a middle layer called the awn hair; and the down hair or undercoat which is very fine and about 1 cm long. Cornish Rexes only have the undercoat.