TCAS II BLK NVG DISP 1/2 071-01619-0226PS 550 Control Unit | TCASII, Black Faceplate, NVG Display, DualThe PS 550 is a Control Unit for use with the MST 67A Enhanced Mode S Transponder. It contains all controls required for transponder operation including TEST, STANDBY, ON (transponder), ALTITUDE an..