... DVR 4.Long distance:2k-3k 5.Low price Optical transmitter*4 channels available to avoid interference*Transmission distance: ... :about 3 hours, depending on the capacity and charging current; 11. Temperature and Humidity requirements: The normal condition should be ... projector, PDA, walkie talkie, Illumination lighting, karaoke player ,and other digital products anywhere anytime.1. DC12V Output Port 2 ...