Remflex 8017 Street & Performance Collector/Reducer Exhaust Gasket, (Set of 2) Street & Performance Headers - 4-Bolt Collector/Reducer Flange Gasket, set of 2 There are no rubber binders or composite materials in Remflex exhaust gaskets so they will not shrink or harden due to time or temperature eliminating the need to go back and continually retighten the flange bolts Remflex exhaust gaskets come in a standard 1/8 Inch thickness and are designed to crush 50 percent allowing them to fill any pits or gaps in the flange surface up to 1/16 Inch Remflex exhaust gaskets come in a standard 1/8 Inch thickness and are designed to crush 50 percent allowing them to fill any pits or gaps in the flange surface up to 1/16 Inch