ABBREVIATIONS EXPLAINED AFM Aluminum Foam Material. A chemically blown, compounded nitrile synthetic rubber bonded to an aluminum core with temperature resistance of over 250°F (121°C). AFM material has an 85% recovery while maintaining strong torque retention. AFM does not require gasket sealers or re-tightening. MLS Multi Layer (Stainless) Steel. The outer layers of the gasket are embossed and coated on both sides with a Viton rubber material. The center or shim layer of the gasket is comprised of an uncoated Stainless Steel layer. MLS gaskets are ideal for any kind of head and block combination. By design MLS gaskets promote an even torque load across the sealing surface allowing for measurable reduced bore distortion. RCM Rubber Coated Metal. A stainless steel core with a thin coating of Viton rubber on both sides. Viton A synthetic rubber and fluoropolymer elastomer with a high chemical and temperature resistance. Has a density of over 1,800 kg/m3, significantly higher than most types of rubber.