Radiator Cap Tester Adapter Tester adapter for the 9300 and MT-300 cooling system pressure testers. Professional grade test equipment to ensure an automotive cooling system is operating at the correct pressure. Made from high quality materials to ensure durability. Designed to test automotive coolant caps. Attachment Type: Threaded End 1 Outside Diameter: 1.88 IN End 2 Inside Diameter: 1.45 IN Gasket Or Seal Included: No Height: 1.67 IN Material: Plastic Prop 65: WARNING: Cancer and Reproductive Harm - www.p65WARNINGs.ca.gov