Harmonic Balancer Bolt, 12-Point Black Oxide AR234-2503Harmonic Balancer Bolt, 12 Point Black Oxidefits GM LS Series (Not LS7) M16 X 2. 0 Thread x 4. 325" UHL, 1 1 16" Socket AR234 2503 234 2503 As The Crankshaft Flexes And T wists, The Balancer Absorbs In credible Amounts Of Kinetic En ergy. To Ensure That The Balan cer Is Locked In Position Arp Has Developed These Ultra Stro ng 200,000 Psi Bolts That Let You Exert Maximum Clamping For ce. Special Features Include 1 4 Thick, Wide Area Washer And An Extra