CNC machined toughest material ever used for small 4 stroke engines. Features a true 1/8" journal radius for strength and durability. Also features airplane wing style counter weights that are proportionaly designed for superior balance. ARC's new #6575 crankshaft was designed for aftermarket flathead blocks that have extra spacing between the crank and cam. Will not fit the Briggs Raptor and Blockzilla blocks and requires large gear set.