The Edelbrock pulley part #15824 allow you to fine tune the airflow and performance of your Edelbrock Supercharger System to your preference. Edelbrock pulley part #15824 is for use with any of our Professional Tuner systems. This pulley features a black Product Features:6-Rib Groove Quantity3.875 in. Outside DiameterAluminum MaterialBlack Anodized FinishSerpentine (Not Included)