Mechanical revolution, length or stroke counters are used within a wide variety of process applications where accurate mechanical length recording or counting is required. Mechanical revolution counters can be specified with many transmission ratios. Transmission ratios are also known as gear ratios and refer to a displayed value per complete revolution of the shaft in either direction. Mechanical stroke counters are also commonly known as lever counters or ratchet counters. They are designed for reciprocating movement within a limited degree of rotation. The transmission ratio is normally 1:1 in one direction only, they are mechanically sprung so they return to a rest position, used for example on hand punch presses, photocopiers, or vending machines where a mechanical movement operates the counter.