Comprised of multiple embossed layers of stainless steel with the outer layers utilizing a Viton rubber coating. Compressed operating thickness is 0.052". All Pro Heads. 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 MLS Head Gaskets. No sealants or re-torque required. GM Gen I Small Block V8 MLX Head Gasket; 4.220in. Round Bore.Comprised of mulitple embossed layers of stainless steel with the outer layers utilizing a viton rubber coating.Compressed operating thickness is .052in. Each. All Pro Heads. .052" MLX Cylinder Head Gasket, 4.220" Gasket Bore. Each