Dual Electret Condenser Cardioid Lavalier Microphone with Windscreens and Clip for Sennheiser Belt Pack SystemBack electret condenser elementPolar pattern cardioidFrequency response: 50Hz–16kHzS/N ratio:>70dBSensitivity: -45dB (+/-3dB)Output impedance: 2.2KO (+/-30%)Maximum SPL: 130dBPower supply: external DC 1.5V-9V power supply for Sennheiser wireless microphone system3' cableConnector: Sennheiser screw lock 1/8'' (3.5mm) plug