This combination smoke and carbon monoxide alarm is hard wired with battery backup for reliable notification in homes apartments hospitals hotels motels and other commercial properties. This is a photoelectric single station smoke alarm with electrochemical sensor carbon monoxide alarm. Features 85dBA alarm horn at 10 feet. 120VAC with 9V battery backup. DUALINK differentiating tones: T3 temporal smoke alarm T4 temporal carbon monoxide alarm. Auxiliary Form A/Form C relay contacts. Relay contacts operate on battery backup. Push button self test feature. Push button functional test feature. Non-latching (self restoring) alarm. Low battery or missing battery indicator. Meets state federal and ADA requirements. Quick-disconnect wiring harness. Connect up to a maximum of 12 Gentex GN-503 combination smoke/CO alarms. 9V battery backup; CSFM listed. Item Weight - 2 lbs.