Cometic Gaskets advanced engineering and manufacturing process allows them to bring you the best availible gaskets for your bike Design engineers have the ability to analyze the environment the gasket will perform in, select the proper material, and apply the appropriate technology to offer the highest performing gaskets available on the market Stock bore head gasket .059" thick CFM-20 perforated steel core with an elastomer surface is ideal for head gaskets allowing heat to be drawn evenly across the gasket surface while providing maximum sealing characteristics when exposed to oils