Arp Replacement Bolts Are Forg ed From Aerospace Alloy And He at Treated Prior To Thread Rol ling And Machining. With An Ex clusive, Flat, 12-point Head D esign And Larger Than Stock Sh ank Diameter These Bolts Deliv er Increased Strength And Impr oved Flywheel And Flexplate Re tention. Rated 170,000psi (hig h-perf.) And 190,000psi (pro-s eries) Tensile Strength.