Finished-Bore Sprockets come with regular keyboard and 2 mounted screws. The keyway is to bolt the sprocket onto the shaft to avoid spinning of the sprocket. One set screw is over the key and one is 90 degrees to the key to lock the shaft. These have two fixed screws and a standard ANSI keyway, except for 1/4, "3/8" and 1/2 "bore sizes. The keyway is the American National Standard Institute (ANSI) standard.
Roller chain sprockets, also called single-strand sprockets, have a row of teeth around a central core, and are used to push conveyors which other heavy equipment in conjunction with roller chains. Fixed bore sprockets are designed to suit a particular shaft size and require a keyboard and setscrew for installation. Plain bore sprockets are made without a keyway or screw set. Machining of keyways or set screws to the exact size needed by the existing shaft and application. Bushed bores have more clamping area around the shaft to provide a safe fit for high torque or high-power applications where the shaft is at risk of sliding, such as paper milling and farm machinery.
Sprockets are of different types, their originator states a limit of productivity for each. Sprockets don't usually have a flange. Many sprockets associated for timing belts have flanges placed around the timing belt. Sprockets and chains are often used for transfer of power from one shaft to another where slippage is not allowable, where sprocket chains are used instead of belts or cables and sprocket wheels instead of pulleys. They can run at high speed and some forms of chain are so constructed that even at high speed they are noiseless.