A type of signal interconnecting jack, used mainly in the musical world as the standard interconnection on modular synthesizer modules that conform to the Modcan-A format. In addition, it is used on synths made by Buchla and Associates to route control voltage signals (but not audio signals). It is also frequently seen on test equipment such as voltmeters, as the jack that the test leads plug into. As in the case of the phone jack, the interconnection cord is nearly always equipped with male plugs at both ends, while the equipment being connected always uses female jacks.