Motorad Engine Coolant Thermostat Seal Gaskets are made from high quality materials suitable for resistance to high temperatures and engine coolant to maintain a good seal. On adhesive backed gaskets, the backing reduces installation time by ensuring proper alignment and ease of installation. Thermostat seals are precision designed and made from high quality rubber products ensuring an accurate fit and durability for a long lasting seal. Inside Diameter: 1.58 in Material: Rubber Outside Diameter: 1.90 in Prop 65: WARNING: Cancer and Reproductive Harm - www.p65WARNINGs.ca.gov Style: Grooved Thickness: 0.17 in