Fire-Lite's SD355 and SD355T addressable, low-profile, plug-in photoelectric detectors use a state of the art photoelectric sensing chamber to provide open area protection and are used exclusively with the MS-9050UD, MS-9200UDLS, and MS-9600(UD)LS Addressable Fire Alarm Control Panels. The SD355T adds thermal sensors that will alarm at a fixed temperature of 135F (57C).