Lunati Pro Series forged crankshafts are top of the line units, manufactured from the highest quality 4340 certified steel. Their 4340 steel forgings meet aircraft quality standards for material cleanliness and purity. Every crank is American forged, American machined and quality checked to meet our exact specifications including: a shaft surface finish of grade 5 RMS or better, journal radii are ground to .140 inch, roundness of each journal is .0001 inch or less and each rod journal is drilled with a 7/8 inch or 3/4 inch lightening hole to reduce the inertia weight of the crankshaft. The Pro Series by Lunati is engineered with high performance street and all-out race engines in mind. Pro Series Crankshafts have been successfully used in 1,500+ HP applications.