Operates as a single unit or interconnected with up to 24 Kidde devices (18 can be initiating).\Features\ - 120 VAC w/ 9V battery backup (battery included)\ - 85 dB at 10'\ - 5 5/8" x 1 9/16"\ - 1 lb \ - 10-year warranty\ - 1/Each Model Number: 1285E|UOM: EA