The Cometic MLS (Multi Layer Steel) gasket is comprised of three layers of Stainless Steel. Cometic uses Stainless steel for increased strength, it's ability to rebound and corrosion resistance. The outer layers of the gasket are embossed and coated on both sides with a flouroelastomer rubber based material (Viton) designed to meet the demands of a variety of harsh sealing environments, load conditions and surface finishes. The Viton coating is heat resistant to 2500C or 4820F. The center or shim layer of the gasket is comprised of an uncoated Stainless Steel layer, which can be varied to accommodate multiple thickness requirements. The MLS gasket is ideal for both aluminum heads to cast iron blocks and aluminum heads to aluminum blocks. Gasket Materials The composition of MLS will also withstand the shearing forces created by aluminum heads on cast iron blocks. No re-torque is necessary. By design the MLS gasket promotes an even torque load across the sealing surface allowing for measurable reduced bore distortion. Available thickness: . 027", . 030", . 036", . 040", . 045", . 051", . 060", . 065", . 071", . 074", . 120"Pit Stop USA offers Cometic 4.030" MLS Head Gasket (Each) - .040" - SB Chevy Brodix C5399-040 at low everyday prices. Be sure to check out all of our products from Cometic including Cometic Cylinder Head Gaskets - Small Block Chevy.