Mazda 3.0L V6/ Ford/ Lincoln/ Mercury (Race Series); 5-7/8 Inch Diameter; 1 Piece Liquid Silicone Filled; Weight 8.1 Pounds/ Rotating Weight 5.4 Pounds; Internal Balance; 10 Percent Underdrive Pulley; Single 3/16 Inch Keyway; High-Grade Steel/ Black Zinc Chromate; SFI 18.1 Certified