Stock ratio 1.625. Fits Big Twin 1984-later, Sportster 1986-later and Buell 1987-later. Replaces OEM 17360-83 and 17375-83. For use with OEM 17611-83 rocker arm shafts or equivalent. Designed to reduce friction in the valve train, providing more horsepower and less heat in the top end. Cast from 4340 chrome moly steel and heat treated. Jims Roller Rockers feature a 660 bronze bushing fit to .007 inches - 0012 inches for the best wear resistance and oil control, along with a roller tip made from beairng grade material to reduce valve guide wear and valve tip galling. Other features include a segmented parabolic pushrod cup which reduces friction at pushrod end and also puts the load on the outer perimeter of pushrod ends. Sold as kit.