Receiver power:3*AA batteries(not include in package list)The transmitter uses a 12V23A alkaline battery(not include in package list)The doorbell can use in office,home, hospital,,restaurant or any where you need it.200 meter receiving distance (In the open area),Stable is perfect for villas, hotels, schools and other areas.The button cannot be placed on an iron door because it will interfere with the signal.Brand Name: Doorbell model:K03DCVolume:4 levels from 0-75dBRingtones:36 pcsReceiver size:120*85*30mmcolor: WhiteMaterial: ABSPackage Content: 1* Transmitter1* receiver1* double-sided tape1* screwsOnly the above package content, other are not included.Note: Light and different displays may cause the color of the item in the a little different from the real thing. The measurement allowed error is +/- 1-3cm.