3-Piece Aluminum Set Includes: 6-Rib Crank Pulley , Non-Ribbed Water Pump Pulley , 6-Rib Alternator Pulley w/ Cover,Marchs serpentine pulley sets have a 25 percent underdrive to free up extra horsepower. They e machined on precision CNC equipment and designed for serpentine equipped engines. Belts not included. Specifications: Fits alternators with external fans only * Includes crank pulley water pump pulley and alternator pulley with nose cover