The XDP Harmonic Balancer Bolt XD628 is an excellent way to securely fasten the harmonic balancer on your Duramax. As the crankshaft flexes the harmonic balancer (also known as a damper) absorbs an incredible amount of energy to smooth out your engine. This bolt will ensure that your balancer is locked into position and features an extra tall 12-point head that accepts a deep socket. This eliminates any worry of stripping the head when torquing to specification. Features: 200,000 PSI RatingExtra Tall 12-Point Head Reduces Risk Of StrippingCold-Forged Custom-4135 Alloy Steel ConstructionXD628 Harmonic Balancer Bolt Torque Spec:Tighten the balancer bolt to 255 ft-lbs using XDP Xtra Slick Engine & Fastener Assembly Lubricant (or similar assembly lube).