The Model C3019A Utility Radio Adapter provides interface between any David Clark Series 3000 Noise Attenuating Headset and a mobile radio system. It's compatible with most mobile radios requiring carbon equivalent microphones. If the radio does not provide DC bias on the microphone audio line, switched battery voltage (13.8 VDC) is required at radio options connector. 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.