Fits FDP-Pro 80CH 5W 128 Channel UHF Handheld Transceiver CB.

Used a lot in security, boating and marine communications 

PTT (push to talk) is on the microphone piece.

Collar Clip on Mike Piece

These Earpiece Mike’s use a Motorola/HYT 2 pin 2 pole plug (M1A) and wiring definition, with a single retaining thumb screw, and o-ring.