This v-pulley serves two purposes. First it allows mounting of a blower pulley to a dampner without having to drill the blower pulley. It also allows an acc. to be driven with a v-belt. The pulley has a register on the back that fits in the dampner as well as a 2.00" male register on the front to keep your supercharger pulley running concentric. This pulley measures .750" thick and has a 6.00" o.d. and is made from billet alum. Included are grade 8 mounting hardware. Uses six 3/8 mounting holes on a 2.782" bolt circle for mounting of supercharger pulley. Fits 4-71 thru 14-71 superchargers.