Made of High Temperature 3-ply Polyester Reinforced Silicone. Maximum Temperature Rating: 350 deg. F (177 deg. C). Ideal for heavy duty pressure connections and provides excellent resistance for high temperature applications Compatible for use with coolant, water, air, turbocharger bypass valve ports, vacuum ports, throttle body water ports, heater cores, and much more. Inside Diameter: 1-3/16' (30mm). Overall Length: 1-3/4' HPS reinforced silicone caps are not compatible with fuel, oil, or any petroleum-based products.