Kidde intelligent addressable detectors are meticulously engineered to deliver high-performance features, superb reliability, and unbeatable quality. With their highly stable design, these detectors resist air movement caused by heating and air conditioning, making them reliable performers ideally suited to modern building interiors. The installation and maintenance advantages of Kidde intelligent detectors add value throughout their service life. Replaceable optical chambers make maintenance a snap, while the head and terminal base design makes short work of installation and maintenance operations. A plastic breakout on the detector housing optionally prevents removal from the base except with a special tool. A bright, easy-to-see single tri-color LED flashes green for normal, yellow for trouble, and red for alarm, thus eliminating much of the guesswork when responding to detector status. The FX-PD houses a replaceable optical sensing chamber that detects particles produced by smoke.