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.
Note: This is a used item. This item might have been taken in on a trade. RBS may have inspected this item and deemed re-usable. There is no warranty expressed or implied with this item.