Check the listing for details. Wireless Doorbell No Battery required Waterproof Self-Powered Door bell Set. Condition: New. Listed at 19.99 USD. HIGHLIGHS [ No Battery Required,Self Power Door Bell ] -No need extra battery for the Transmitter,press and transform kinetic energy into electric energy.then the transmitter release signal to active the door bell receiver.Save the energy to change battery and environment friendly. [ Strong Signal ] -Over 150 meters(open space) effective range and strong ability to penetrate wall,available for big house. [ IP68 Waterproof ] -Rainy days can be used ,safe &durable. [ One Transmitter can Pair with Several Receiver ] -no need worry miss the door bell ring of every important visitor [ 38 Kinds Ring Tons&4 Level Volume Adjustable ] -in total 38 kinds ring tons available,4 level volume adjustable,including mute.Fully satisfy your different requirement in different scene and room. [ Easy to Install ] -Transmitter button can be paste on the door via double side tape,or screw on the wall with the bottom plate. And the receiver bell can be plug in any home outlets. [ Pager for Vulnerable Group ] -it can be used as a pager for old people,kids,pregnant women,efficient and reliable. SPECIFICATION -- Operation Voltage:100-240V -- Power Consumption:0.25W -- Wireless Frequency:433MHz -- Operation Temperature:-10 - +45℃ -- Ringtone Volume:≧50db/m -- Wireless Distance:150 meters(open space) -- Receiver Size:95*54*68mm -- Transmitter Size:80*50*28mm -- Transmitter Power Type:Self Power