The Model C3019B Utility Radio Adapter provides interface between any David Clark Series 3000 headset and a mobile radio system. The Model C3019B is compatible with most mobile radios requiring amplified electret (carbon equivalent) microphones. It is not compatible with radios which do not provide DC bias on the microphone audio line. The adapter is generally attached to the wearer's belt but can be used in any convenient location. Select a location that allows freedom of movement while providing access to the PTT switch.