3/4 pitch duplex pilot bore sprocket 21 tooth 12B-2 Sprockets are rotating toothed wheels which are used to transmit power or convey materials by engaging with roller or conveyor chains. Key specifications include the intended application, material, number of teeth, and pitch as well as the physical dimensions as required. Sprockets are used primarily in chain driven systems to transmit power or rotation to other shafts. An example is a bicycle sprocket that transmits rotation from the pedals to the wheel. Sprockets may also be used to convey material from place-to-place as in the case of overhead conveyors. Sprockets come in a variety of tooth configurations depending on the intended application and chain type.