Description:RF Resistant Mini-Boundary Condenser Microphone.Miniature installation button style condenser boundary mics for use in teleconferencing or voice lift sound reinforcement. Other applications include surveillance, ambient recording or audio observation. Improved RF immunity to greatly reduce susceptibility to radio interference from cell phones, PDA or similar two-way communication devices. Available in cardioid in black (201R). Metal nut/washer hardware supplied.Metal nut/washer hardware supplied.Specification: Operating Principal:Permanently-Biased Condenser Polar Pattern:Cardioid, Omnidirectional Frequency Response:90Hz – 17KHz Sensitivity:-32dBV (25 mV) @ 1 Pa Impedance:150 ohms Max SPL:129dB Self Noise:29dBA Power Requirements:P12, P24, P48, 2.4mA