1、The frequency is fixed, it can be used at boot, convenient. 2、Four-channel volume is independently adjustable, providing 1+4 audio output, and four-channel audio output is independently controllable. 3、Handheld/collar clips in the transmitter can be used in a mix and match. 4、5 sets of different frequency points can be used simultaneously. 5、Very suitable for stage performance. This product adds several new domestic unique technologies based on the original microphone technology, which makes the system have ultra-high sensitivity, strong anti-interference ability and excellent stability. The original technology includes high-efficiency low-cost RF emission technology and SMT production process in the United States, and uses a locking frequency of better than 10ppm quartz crystal, dynamic audio compression, expansion circuit, image frequency suppression circuit, switch-time shock elimination circuit, anti-return circuit Variable output control technology, computer EDA, analog online assisted design, etc. Features: 1. The frequency is fixed, it can be used at boot, convenient. 2. Four-channel volume is independently adjustable, providing 1+4 audio output, and four-channel audio output is independently controllable. 3. Handheld/collar clips in the transmitter can be used in a mix and match. 4. 5 sets of different frequency points can be used simultaneously. 5. Very suitable for stage performance. 6. Lightweight, mini size. Easy to carry. Specification: Model: U-F4000 Weight: about 896g/31.61oz (transmitter), about 270g/9.52oz (receiver*4) Size: about 48*19*4cm/18.9*7.48*1.57in (transmitter), about 11*6.3*2cm/4.33*2.48*0.79in (receiver) Battery: AAA*2 (Not Included) Transmit power: <30mW (depending on applicable national regulations) Harmonic power: <40dB (main wave) Battery life: >10 hours Oscillation mode: quartz crystal oscillation Stability: 10PPM Wireless interface: BNC/50Ω Maximum frequency offset: 50KHz Signal to noise ratio: >105dB Distortion: <0.5%@1KHz Image interference: >85dB Adjacent frequency interference: >75dB Frequency response range: 60Hz~16KHz Squelch control mode: multiple squelch circuit Maximum output level: +10dBV Sensitivity adjustment range: 12-32 dBμV Power supply: external DC power supply, 0.8A, 12~15V DC Use distance: Open environment: 50-80m Complex environment: 30-40m Frequency range: 621.5~643.7Mhz Package List: 1 * Transmitter 4 * Receiver 1 * Instruction Manual 4 * Microphone 1 * Charger 1 * Audio Cable 2 * Antenna