... effect, high anti-resistance, Volume & Channel display, 30channels... 2.4G Digital Wireless Tour Guide System Features & Specifications:1. Transmit ... frequency 2400-2480 MHz; Complete digital audio transmission.2. Channel & Volume Display function. Channel 40 Max; 6 ... . Ultra-low power consumption, 8hr.work time for transmitter and 20hr.continuous work time for receiver.6. Rechargeable ...