ACDelco 31741 Professional Premium Formable Coolant Hose Inside hose diameter remains constant from end to end. No convolutions inside of the hose so tube is smooth, allowing coolant to flow freely Comes with protective sleeves to help duplicate GM OE designs for proper fit and function Extra strength fabric reinforcement with helical steel wire spiral molded between the tube and cover provides excellent flexibility as well as collapse and kink resistance Heat resistant construction throughout for increased durability EPDM rubber tube and neoprene cover for extended service life