ARP Fasteners are the highest quality in the industry. ARP's automotive racing fasteners are precision made using certified SDF or CHQ quality material (better than aircraft-quality). ARP Fasteners are used by leading teams in nearly every form of racing, from Indy to Formula 1. These super high strength fasteners are made in Southern California especially for use in high performance VW engines. ARP HD main studs and head studs provide 190,000psi tensile strength. All stud kits come complete with parallel-ground washers and aerospace quality nuts. ARP HD rod bolts provide 190,000 to 220,000psi tensile. That's at least 40% stronger than original types! Threads are rolled to Mil-Specs after heat treatment, ensuring the best possible fastener.Recently added are the superior Undercut Head Studs. Undercutting the shank of a stud increases its flexibility and spreads clamping loads more uniformly, resulting in a more consistent torque setting over many heat cycles. The Rod Bolt Stretch Gauge is a must for serious engine builders. It is the most accurate way to determine the correct pre-load in the rod bolt. Measure the bolt before starting and monitor overall length during installation. The correct preload or torque has been applied when the bolt has stretched the specified amount. ARP better-than-aircraft quality 8740 steel fasteners are recommended for any all-out performance motor. Don't let an ordinary stock bolt destroy your big investment!Factory stretch bolt WARNING! All VW factory head bolts and rod bolts on 1.8L and larger engines are one-time use bolts and cannot be re-used! Make sure that you replace these each time they are removed for any reason.