Gasket material and construction will vary by application to ensure longevity with leak free performance under all conditions. 4-stroke applications utilize a double-sided Viton® rubber-coated stainless steel gasket providing precise, high-temperature sealing capabilities in all conditions. Exhaust gasket kits are made for extreme temperatures, utilizing a steel-tanged outer layer that bites into the Armor-400 inner layer (heat-resistant to 1,800 degrees Fahrenheit), providing ultimate strength from blow-outs or push-outs created by over-torqued situations. Made in the U.S.A..