Edelbrock 3.25in. part #15873 pulley allow you to fine tune the airflow and performance of your Edelbrock Supercharger System to your preference. Edelbrock pulley is a 8-rib design for use with any of our Professional Tuner systems. Edelbrock pulley feature a black anodized finish.- 3.25in. 8-Rib Edelbrock's/C Pulley in Black Finish for - Pro Tuner System