The 2151 low-profile photoelectronic detector uses a state of the-art optical sensing chamber. This detector is designed to provide open area protection and to be used with compatible UL listed control panels only.The capability of plugging this detector into a variety of special bases makes it more versatile than equivalent direct-wired models. Two LEDs on each detector provide local 360° visible alarm indication. Theyflash every five seconds indicating that power is applied and the detector is working properly. The LEDs latch on in alarm. LEDs will be off when a trouble condition exists indicating that the detector sensitivityis outside the listed limit. Remote LED annunciator capability is standard and may be implemented through an optional accessory RA400Z. The alarm can be reset only by a momentary power interruption. This detector may be tested by activating the internal reed switch with a magnet.