Wireless microphone headset system: [Only for Mic Jack, Not support Aux/Line in Jack]The receiver has 1/4" plug connect, works with Mixer, Pa system speaker, desktop, speaker and amplifier. ???Support 15 sets of microphones working simultaneously in different frequency bands without interfering with each other. ???Change channel to avoid interference: Long press volume "?????? button of the transmitter until the blue light flash 3 times, then stay on. [???Not Compatible Bluetooth Speakers/Macbook???]. Professional UHF Wireless Mic Performance: Upgraded Bietrun wireless microphone, FCC certified UHF independent frequency bands, high-sensitivity condenser microphone. ???Stable & Comfortable ???165 feet (50m) transmission distance ???Signal stability ???No delay ???No radiation ???Anti-howling ???Anti-jamming ???Constant frequency ???Clearer sound quality. Easy to use: Please turn on the transmitter and receiver power switches, the blue light will flash for approximately 2s. Indicator light stops flashing after a successful match, then you can use it. No further operation. ???Headset and handheld is 2 in 1 design, easily change the handheld mode to headset mode to meet your needs. Charge & Work of Upgrade Microphone: Built in newest upgraded 450 mah rechargeable lithium-ion batteries, transmitter and receiver can be charged simultaneously with the dual usb v2.0 cable head. Fully charge is only 2.5 hours, working time upgraded to 6 hours. No Sound?: 1. Check if the connection is secure. 2.Check if a speaker with MIC is connected. (How to re-pair: ???turn on transmitter and long press key ???+ and -??? for 5 seconds simultaneously, indicator light starts flashing(blue). ???turn on receiver, wait for auto pairing about 5s. ???indicator light stops flashing after a successful pairing). Please note: it's a microphone device for voice input, no auditory function, no speaker.1-year warranty, contact if any questions.