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 LL8 Atlas .040" MLX Cylinder Head Gasket, 3.710" Bore. GM 4.2L INLINE 6 VORTEC 4200