120 volt AC powered ionization smoke alarm with safety light and 9 volt battery backup This premium smoke alarm has the ability to function as a stand-alone unit or in an interconnected system Offers Hush feature that temporarily silences nuisance alarms Installation is simple with twist-off mounting plate and requires no wiring Includes a quick connect power harness making installation simple and easy Includes two 9 volt battery back up, providing continuous protection even during a power failure Includes dust cover to protect sensor during construction Red LED flashes every 30-40 seconds to indicate power Green LED indicates presence of AC power Test button tests units electronic circuitry, horn, and battery function