*** IN STOCK SHIPS TODAY *** Billet aluminum blower pulley spacer includes grade eight bolts and washers. 2.00" register bore, six .375" mounting holes on a 2.782" bolt circle. Fits 4-71 thru 18-71 roots and screw superchargers. Outside diameter of blower pulley spacer is 3.375".Racer can pick spacer thickness from drop down menu.