Lovin Product doorbell have 3 items. (1 Receiver&1 Push Button, 2 Receiver&1 Push Button, 2 Receiver&2 Push Button) A perfect use case scenario for these products: 1 Receiver&1 Push Button This item also can be used great for commercial space and offices. This item also works well for large homes or villas. This item also can be used as a simple alert device. A paging device for the elderly, can signal for care when they need it most. 2 Receiver&1 Push Button A perfect use case scenario for this product would be if you can put one receiver on the first floor, the another one in the basement, garage, or second floor. If someone pressing a single transmitter button. two receivers play same song. No matter where，you know that the guest come. Specifications Wireless Range: 1000ft maximum in the open air Internal Sounds: 36 Chimes Volume: 4 level adjustable levels (25db to 85db) Receiver Power: AC 110V ~ 220V 50Hz / 60Hz Transmitter Power: 1 x 12V 23A battery Package Includes 1 x Push Button (Transmitter) 2 x Plugin Chime (Receiver) 2x Screws 1 x Double-Sided Adhesive Tape 1 x 12V 23A battery for Transmitter 1 x Screwdriver 1 x User Manual Note: Add on more receivers: Plug in the receiver. Press the volume button (the second button) of the receiver for 3 seconds and hold it, it enters the pairing mode. Then press the doorbell that you want to pair. After the pairing, lose the volume button.