The SL-200QDM is a 60m outdoor active infrared (AIR) beam set designed for perimeter security. This wired quad beam set features four selectable channels for easy stacking in beam towers. It includes dual modulation and power auto-adjustment for reliable signal transmission between the receiver and transmitter, even in strong sunlight or harsh weather conditions. The system also includes high-grade aspherical lenses, an LED, and a sound gauge for enhanced performance.