Sprockets are teeth like projections arranged on a wheel rim to engage the links of a chain. They engage chains in many different power transmission and conveyor systems. They are mainly made of cast iron, sintered metal, and carbon steel. Inserted sprockets are also designed to reduce noise and operation. The sprocket must be inspected once a month for wear and if the teeth are worn down or are broken they should be replaced.

They are often an economic, reliable drive system for long running, continuous drive applications with maximum absorption of shock and minimum torque loads. The sprockets and the chain must be lubricated with chain lube such as bell ray. Sprockets are most commonly used in bicycles.