TCAS I BLK NVG DISP 1/2 O/O 071-01618-0212Primus II Select Control Head | TCASI, Black Faceplate, NVG Display, Dual, ON/OFFThe PS 578 is the control unit for use with MST-67A Enhanced Mode S Transponder (-2001/2101 versions) and contains all controls required for transponder operation including TEST..