System Sensor i3 series smoke detectors represent significant advancement in conventional detection. The i3 family is founded on three principles; installation ease, intelligence, and instant inspection. This smoke detector features a plug-in detector line with mounting base included, large wire entry port and in-line terminals with SEMS screws. Mounts to octagonal and single-gang back boxes, 4-square back boxes, or direct to ceiling and has a built-in test switch.