Space Age Electronics RT-3000 DUCT SMOKE DETECTORS, from Space Age Electronics come with weather-tight NEMA 4X rated corrosion resistant enclosures and can be installed in both horizontal or vertical configurations. A flip of the cover latch releases or secures the NEMA 4X enclosure too. Other features include a next-generation control board with color-coded, trade-dedicated output terminals; Twist-in photo or ion sensor heads; A push-button timed Maintenance Mode; and a uniquely constructed chassis that prevents accumulation of condensate commonly generated by the severe temperature changes. They also have 180° visibility for all visual indicators (with cover in place) and interconnect (up to 30 units) for common functions. UL and CSFM listed.