The TS7 Series features photoelectric smoke detectors with an easy to install and maintain head and base design. The photoelectric smoke detector heads are self diagnostic and have field replacable optical chambers. They feature automatic drift compensation which adjusts the alarm sensitivity when the detector gets dirty. The TS7 smoke detector heads meet NFPA 72 field sensitivity testing requirements withut the need for external meters. The TS7-2T and TS7-4T models in the TS7 Series feature rate of rise and fixed heat sensors for quick detection of both flaming and smoldering fires. The TS7 Series offers six inch bases to support either two or four wire smoke detector heads. Four inch bases are sold seperately.