A widely used connector for professional sound applications typically having three conductors for mono connections (or five conductors for stereo connections) plus an outer shell which shields the connectors and locks it in place. The connectors either consist of pins (a.k.a. ‘M’) or sockets (a.k.a. ‘F’). Microphones and mixer outputs usually have pin connectors while mixer inputs and camera inputs have sockets. XLR connectors are designated with the pin count and whether they are plugs (‘M’) or sockets (‘F’), e.g. XLR-3M.