XM-W4 Pro UHF Wireless Microphone System with Lavalier for Nikon D300, D300s, D500, D3200, D3300, D600, D610, D700, D750, D800, D800e, D810, D810A, D5100, D5200, D5300, D5500, D7000, D7100, D7200 DSLR Transducer type: Condenser (unidirectional) Frequency response: 35 Hz - 20,000 Hz Nominal / Load impedance: 200 Ohm or less Sensitivity (Short) Long: -40 dB/ +/- 1dB / 0dB = 1V/Pa,1kHz Signal Noise: 75 dB or more