.010" thick RCM (Rubber Covered Metal). With silicone bead. Type 'B'. James' RCM gaskets consists of a .020" thick stainless spring steel base covered with a .001" thick heat resistant Viton rubber on both sides. A very strong gasket which requires no re-torquing. Gaskets will not become brittle or burn out. Note: The Type B' was introduced on Evolution XL Sportster models in 1986, and will fit all Evo XL models, but also all 84-99 Evo 1340cc models although the Big Twin cylinder base is a bit larger than the gasket. The 'type B' is the only gasket type that 'The Factory' supplied from 1986 onwards for both Evo Big Twin and Evo XL Sportster models.
