Check the listing for details. CLOCKAUDIO C301E RF Back Electret Condenser Cardioid Microphone TESTED Good!. Condition: Used. Listed at 30.00 USD. The Electret condenser microphone has a cardioid polar pattern and slimline profile design. The microphone is constructed from high quality brass construction and is fitted with a knuckle joint allowing horizontal rotation and vertical adjustment. The microphone is fitted with a phantom power adapter accepting 9 to 48 volts DC and has an impedance of 200 Ohms. The Phantom Power Adaptor includes filters which will eliminate all cellular frequencies (GSM/2G, 3G, 4G & 5G) and is terminated with a full-size male 3 pin XLR. Frequency response: 50 Hz - 18 KHzSensitivity: -40dB ± 3dB @ 1KHz (0dB =1V/Pa)Total Harmonic Distortion (THD) at an operating level of 125dB less than 1%.Shaft diameter: 8mm.Finish: Satin Black