Suit Gm Ls Series (Not Ls7) M16 X 2.0 Thread X 4.325 In Uhl. 1-1/16 In Socket. As The Crankshaft Flexes And Twists The Balancer Absorbs In Credible Amounts Of Kinetic Energy. To Ensure That The Balancer Is Locked In Position Arp Has Developed These Ultra Strong 200000 Psi Bolts That Let You Exert Maximum Clamping Force. Special Features Include 1/4 Thick Wide Area Washer And An Extra Tall 12-Point Head That Accepts A Deep Socket And Aliminates The Worry Of Stripping The Head.