Astatic 636L Noise Canceling Mic CB Radio 4 pin Cobra - Astatic 636LB1 Rugged Housing Design Dynamic Noise Canceling Microphone, black cycolac case Frequency Response: 100Hz - 8kHz, Output Level @ 1kHz Output Impedance: 2000 Ohms (Matches 600-5000 Ohm Inputs) Designed for Close Talking Handheld Applications Bulk packed (No Package)