Feature:1. Self Generating: The transmitter has a built in power generation module, no batteries, no wiring, beautiful and easy to put in place. No need to worry about the battery.2. Super Signal: The wireless signal of this doorbell has strong penetrating power, the signal can penetrate 3 or 4 walls and up to 150 meters in the open area.3. Music Bell: This doorbell has loud volume. The sound quality is thick and dynamic. There are 38 musics for you, including the classic doorbell sound and music ringtones.4. Waterproof: This wireless doorbell with waterproof design, even if it is raining, it does not affect the use. It can be installed in the outdoor.5. Widely Used: This doorbell can be used in homes, villas, hotels, factories, office buildings, etc. It can also be used for the elderly, patients and pregnant women to call with one key.Specification:Item Type: Wireless DoorbellMaterial: ABSWeight: Approx. 120g/4.23ozApplication: For families, villas, hotels, factories, for the elderly, the sick, pregnant women one key callDoorbell ParametersPower Supply: Self GeneratingTransmission Distance: Unobstructed 150mRF Frequency: 433MHzReceiver ParametersRinging Tone: 38 Songs (4 Adjustable Levels)Ringing Volume: 50DB / at 1m .Package List:1 x Doorbell1 x Receiver1 x Sticker1 x InstructionNote:Please supply power according to the voltage in use, use other voltages may cause fire and product damage!