Photoelectric smoke detector. Plug-in detector line mounting base included. Large wire-entry port. In-line terminals with SEMS screws. Mounts to octagonal and single-gang backboxes, 4 inch square backboxes, or directly to ceiling. Stop-Drop'N Lock attachment to base. Removable detector cover and chamber for easy cleaning. Built-in remote maintenance signalling. Drift compensation and smoothing algorithms. Simplified sensitivity measurement. Wide-angle, dual-colour LED indication. Loop testing via EZ Walk feature. Built-in test switch.