This is a virtually complete RAF IFF Mk.IIIG as used on Spitfires and Lancasters etc. The British made Mk.IIIG IFF consisted of the Receiver R3121, a remote control unit and antenna. The IFF or "Identification Friend or Foe" picks up the signal from allied radar installations and returns a coded signal to radar operator. If the radar operator does not receive coded return the target can be identified as an enemy aircraft. The electronics were considered secret, therefor it could also be fitted with an inertia switch and an explosive charge to destroy the secret electornics inside should the aircraft crash behind enemy lines. The installation was also manufactured under Lend-Lease as the SCR-695 and used on most allied aircraft, British and US. The rare installation on offer is in very good and virtually complete condition. All the connectors are there but the cables are not completely joined up yet.