There is a small receiver unit to connect to the PTT connection of the aircraft radio interface. The PTT and receiver then replace the need for a cabled PTT. There is a small 12w volt battery in the PTT unit. Battery life is typically 2-4 years, depending on amount of use. The receiver is fitted inside a small plastic enclosure and simply plugs into your existing radio interface, or the reciever can be installed inside your radio interface. Compatible with all makes of intercom systems.