3/8 In Suit SB Ford. Fits Most Ford Small Blocks With 3/8 In Screw-In Studs. ARP High Performance Series Rocker Arm Studs Are Ideal For Et Bracket Racing Limited Rule Oval Track Competition Or Street Use. Made From 8740 Chromoly Steel And Are Heat-Treated To 180000 Psi Tensile Strength They Are Concentric Within .005 T.I.R. Thread Pitch To Thread Pitch Which Will Give You More Consistent Rocker Geometry