Wireless Microphone System Handheld LED Mic Speaker with Portable USB Receiver for KTV Speech Amplifier Recording Free frequency modulation, adopts UHF 676MHz to 607 MHz frequency band, strong anti-interference, applied to Karaoke, party, business meetings, speech or other outdoor and indoor activities. Features: Wireless handheld microphone system for karaoke, party, business meetings, speech or other outdoor and indoor activities. Adopts UHF 676MHz to 697MHz frequency band (channel A: 677MHz-686MHz; channel B: 687MHz-696MHz), strong anti-interference. With automatic mute and shock elimination circuit avoiding the impact and noise of the switching, extremely high pick-up sensitivity and fine tone quality make your speech or singing more clear. The wireless transmission distance is about 30 to 50 meters, multiple devices can be used simultaneously without interference or frequency hopping. Specifications: Microphone quatity: 1pcs, 2pcs (optional) Frequency response: 676-697MHz Oscillator: DSP chip frequency lock Frequency stability: ±10ppm Distortion: ≤0.5% Sensitivity: -95 to 71dBm Sound frequency: 40-18000Hz SNR: ≥ 90dB RF power: 10dBm Audio output: 1/4" unbalanced output 300mV Receiver battery: 3.7V, 150mAh Microphone battery: 2 * AA battery (not included) Receiver size: 125 * 35 * 20mm / 4.9 * 1.4 * 0.8in Receiver weight: 49g / 1.7ounce Microphone size: 230 * 40mm / 9.1 * 1.6in Transmitter weight: 203g / 7.2ounce Package size: 285 * 140 * 100mm / 11.2 * 5.5 * 3.9in Package weight: 1pcs Microphone: 470g / 1.0lb 2pcs Microphone: 670g / 1.5lb Package list: 1pcs Microphone: 1 * Microphone 1 * Receiver 1 * Antenna 1*  USB Cable 1 * 3.5mm Converter 2pcs Microphone: 2 * Microphone 1 * Receiver 1 * Antenna 1*  USB Cable 1 * 3.5mm Converter