Frequency Adjustable: Dual UHF wireless microphone system. Employs PLL frequency synthesized technology to provide hassle-free sound transmission, minimum dropouts, and maximum feedback rejection. Smooth and quick IR synchronization. Long range operation of 200ft – 250ft line of sightAnti-interference feature: karaoke wireless microphone equips with auto scan function, which enables system to search for the least interference channel to pair up with transmitters. 2 antennas design increases anti-interference ability and decreases interference between each channel. Microphone Easy to Use, Plug and Play, Automatic Pairing: Plug the receiver into the MIC jack Only , but not into the AUX jack. Then turn on the entire system, the receiver will automatically synchronize its frequency with the microphones. Adjustable Volume Control. Perfect for indoor, outdoor, karaoke, party, church, meeting, wedding, speech, class, opening ceremony, promotion, DJ, small live performance on stage, professional engagement or religious event, etc.