Moroso alternator round tooth pulleys are designed to work more efficiently and take less power to drive. They use a .500 in. wide drive belt, and with a wide variety of drive pulley sizes, any drive ratio you may need is achievable. These pulleys are made to accept a .590 in. diameter shaft alternator. Moroso radius tooth drive pulleys are designed with the same 8mm tooth technology and will add to the efficiency of the entire round tooth drive combination. They come available in sizes that will not only give you the ratio that you want, but will also adjust the centerline measurement between your alternator and crankshaft center. Moroso drive pulleys fit any 1.00 in. mandrel with a 1/8 in. keyway slot.