The one-shot (also called a monostable multivibrator) is essentially an unstable flip-flop. When a one-shot is set by an input clock or trigger pulse, it will return to the reset state on its own accord after a fixed time delay. Hence a one-shot is able to generate a pulse of a particular width following an input pulse. One-shots are often used in pairs with the output of the first used to trigger the second. Unfortunately the time relationship between the signals becomes excessively interdependent and it is better to generate signal transitions synchronized with the circuit clock.