Wireless door chime plugs into any standard wall outlet, no batteries required. Signals pass through doors, walls, and floors. 2 note tone front door, 1 note rear door. Up to 75' range. 128 selectable codes. Includes 2 push-buttons (white with white push bar, white with beige push bar) powered by a 12V alkaline battery type MN21 or A23 (included). 3.5" W x 5.125" H x 1.25" D. 1 year warranty. UL (Underwriter's Laboratories) listed. White.