Mr. Gasket Big Block Chevy Harmonic Balancer Bolt Kits feature a high hex head that prevents socket slippage when adjusting valves or rotating the engine to degree in a cam. Designed specifically for big-block Chevys and heat-treated to Grade 8 specs, these bolt sets come with extra-thick parallel-ground washers that deliver a smoother, more accurate, more uniform torque. They're ideal for high-performance, drag race, and circle-track applications and come complete with split lock washers to prevent any loosening caused by vibration.