A Gentex photoelectric type smoke alarm. Unit is hard-wired (you will need an electrician to hook it up). Features: 90dB solid state non-latching piezo T3 audible horn Functional test switch - patented three position test Pulsing LED sensing chamber Solid-state LED condition indicator Maintenance indicator Quick-disconnect wiring harness Mounting hardware adapts to standard junction boxes Wall or ceiling mount UL Listed (USA) Options available: Gentex 9123 ($54.95) Tandem connection of up to twelve units Gentex 9123F ($59.95) For use with Gentex remote strobes Tandem connection of up to six units One set of Form A/Form C contacts