Cometic Chevy Gen1 Small Block V8 .040in MLX Cylinder Head Gasket-4.220in Bores-Round BoreComprised of multiple embossed layers of stainless steel with the outer layers utilizing a Viton rubber coating. Compressed operating thickness is 0. 040". With Steam Holes. Cometic MLX (Multi Layer Stopper) gaskets utilize an integrated stopper layer for combustion chamber sealing and improved clamp load around the cylinder without increasing bore distortion. MLX technology can be found in some head gaskets and are made from the same materials as our