Below is a general manufacturer product group description. Please note the information below is not item specific. Item specifics are above in product details.

Cometic Head Gaskets are developed with the performance enthusiast in mind. With so many individual requirements for each motor Cometic offers a number of options to suit your specific motor and needs.
MLS
The Cometic MLS 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.
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.
CFM-20
A perforated steel core with an elastomer surface is ideal for head gaskets allowing heat to be drawn evenly across the gasket surface while providing maximum sealing characteristics when exposed to coolants and oils.
COPPER