WHM06 Home Door Bell 38 Ringtones USB Powered Wireless Doorbell (2 Transmitters+1 Receiver) ?Crafted from high-quality material,ensuring reliable performance ?Provides 38 kinds of ringtones and 3 levels of volumes for you to choose from,you can select the music you want according to your preference ?Easy to install. Just plug the receiver into a USB port,and mount the button transmitter on the wall,door or anywhere you want ?Great for large houses,apartments,offices,classroom,etc Specification: ?Operating voltage: 5V (USB power supply) ?Power consumption: ?��0.25W ?Operating frequency: 433.92MHz ?Operating temperature: -10??~45?? ?Controllable volume: ?Y50dB/1m ?Remote control distance: ?Y150m (open space) ?USB receiver size: L43xW41xH32mm ?Transmitter battery: 23A 12V 60mAh battery (2pcs: totally 120mAh) ?Transmitter power consumption: