Product: Set of Wireless Microphones Dynamic Microphone Type Relevant Items: Seminar, Theater, KTV, Residence, Instruction, Vocal, Show, Lecture Lock noise for mute control. Deviation in frequency: ± 11 kHz Response frequency range: 80Hz–15kHz Stability of frequency: ± 0.005% 0.5% distortion at 1 kHz There are two channels available. Attenuation: -70dB M 50 meters is the operating distance in an open area. Power supply for receiver: 3V AA batteries power the transmitter. 20mW of transmit power Range of frequencies: 200MHz–270MHz Method of output: mixed and independent automatic selection