A US army air force flux gate compass transmitter as used on B-17 and other heavy bombers. The compass transmitter was placed in the wingtip of the aircraft, far away from electrical and magnetic interference to give a very accurare compass reading. Via an amplifier it drove the Master indicator at the Navigator's station (I have a master indicator listed as a seperate item). This was probably the best compass system develeped in WW2. The compass transmitter is good conditin with a 1942 dated serial number.