Cobra CA M29 BT Replacement 6-PIN CB Microphone for Cobra Bluetooth CB Radios Features Bluetooth Wireless Technology Noise-Canceling Microphone With 6-Pin Connector. Will NOT work with 4-Pin Works w/following models: 29LTDBT, 29LXBT, 29WXNWBT Special Noise-Cutting Circuitry. Dynamic Noise-Canceling Circuit. Voice Coil Diaphragm Metal Mesh Grille. Coiled 9 foot cord