RTS has teamed up with ARP to supply customers High Performance Series flywheel bolts far superior to OEM hardware. They're forged from aerospace alloy and heat-treated prior to thread rolling and machining. They feature an exclusive, flat, 12-point head design and a larger-than-stock shank diameter, for increased strength and improved register. Suits Ford Windsor, Cleveland, FE 390-427, 429-460 Chevrolet all Small Block, Big Block with 2 Piece Seal