Astatic 636L 4-Pin CB Radio Microphone W/ 6-Pin RCI Radio Compatible Adapter Noise Cancelling Dynamic Microphone (for close talking) Has a rugged , dependable dynamic element in a "TEAR DROP" style housing Heavy duty coil cord extendes to 71/2 feet. Wired with 4-Pin plug for Cobra, Uniden & Galaxy etc. Output Level: -56dB. Impedance: 400 ohms , matches 50 to 1000 ohms C4PRCI6 ADAPTER: Converts a 4-Pin wired mic to be compatible with a 6-Pin RCI radio