Fits Twin Cam 1999-later. Standard 3 3/4 inch bore size with .030 thickness. Extreme sealing technology (EST) will eliminate head gasket problems. These are top quality for everything from 8.5:1 compression ratio up to 15:1 plus. Three-piece design features an aluminized stainless steel center sandwiched between two NBR coated stainless spring steel outer layers. To ensure the utmost sealing power, the outer layers are embossed at the cylinder bore and the oil drain backs provide a seal so effective that O rings are not required. Distributes heat exceptionally well from the head to the cylinder, thus eliminating hot spots that would normally cause a head gasket failure. Sold in pairs.