These Genuine James cylinder gaskets and kits are to rebuild the top end of an SandS engine or Total Performance Engineering engine, or any other engine with SandS cylinders and cylinder heads. Available as a set of head and base gaskets, or pairs of head- or base gaskets. Head gaskets feature a Firering and are .046" thick that will crush to .042". Base gaskets are .022" silicon beaded metal that will crush to .020"