Pro Copper Head Gaskets for Chrysler 354-392ci Early Hemi. Bore Opening: 4.060″; Gasket Thickness: .062″; Material: Annealed Copper; Bolt holes will accommodate 9/16″ studs. These gaskets have all water passages for use in boats, street driven, and liquid cooled race engines. *Pro Copper head gaskets require O-rings in the block or head* For self sealing copper head gaskets for use with O-rings please see “Titan” series head gaskets. For self sealing head gaskets for use without O-rings please see “ICS Titan” series head gaskets.