Fits 4-71 thru 18-71 roots and screw superchargers. Pulley has six .375" mounting holes on a 2.782" bolt circle. One bolt hole has been elongated to fit with older crank hubs that use the one offset bolt hole.
Pulley has some rub marks on the teeth which can be seen in the pictures, double click the picture to make sure the rub marks are not a issue before purchasing.