These Pro series cylinder head bolts from ARP are cold-forged to ensure molecular integrity. They are heat-treated prior to thread rolling and machining, and are rated at a whopping 190,000 psi. The Pro series are also available with hex and 12-point heads. All kits come complete with hardened parallel washers for even load distribution and accurate torque readings. This head bolt kit fits LS2, LS3, LS7, and LS1/LS6 built after mid 2004.