System Sensor single-ended, reflected-type Beam Smoke Detectors are perfect for protecting open areas with high ceilings where other methods of smoke detection are difficult to install and maintain. Beam Smoke Detectors feature a 4-wire design and are easier to install than dual-ended projected beam detectors because alignment is accomplished via an optical sight and a built-in, two-digit signal strength meter. Available with an integral sensitivity test module, these detectors provide 16- to 328-foot protection coverage in a broad operating temperature range (-22