A device used to achieve synchronization between two or more pieces of equipment. Traditionally synchronizers have been hardware devices that compare a reference signal (often some type of time code) from the machines needing to be synchronized. By also having control over their speed and transport controls it is able to make the two machines play “in sync” (sometimes mistakenly called “lock up“) with one another. Synchronizers are used in many different facets of audio and video productions and come in a correspondingly wide range of configurations, price ranges and capabilities.