ACDelco 16421M Professional Molded Heater Hose Comes with a protective sleeve to help duplicate GM OE designs for proper fit and function Installs without buckling, bending out of shape, or straining at the connection for easy installation Has all the quality features of a regular coolant hose for interchangeable use Its diameter ranges from 1/4 in to 1 in to fit different types of vehicles Less than 500 part numbers cover more than 1,200 applications to maximize coverage and reduce inventory