MLS gaskets are made from stainless steel, and while very strong, stainless steel is very hard, they do not conform to anything, head and block must be machined very smooth and flat. I know MLS gaskets are all the rage right now, but this old school guy likes copper head gaskets with an O-ring in the block. Top Fuel still uses copper head gaskets, and money is not an object, so why do they use them? They work. I have seen MLS gaskets leak water between the layers as well. MLS gaskets were designed to fix the OEM issues with head gasket failures in the 80's and 90's which they did.