Features: 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 Doorbell_x000D_ Material: ABS_x000D_ Weight: Approx. 120g/4.23oz_x000D_ Application: For families, villas, hotels, factories, for the elderly, the sick, pregnant women one key call_x000D_ Doorbell Parameters_x000D_ Power Supply: Self Generating_x000D_ Transmission Distance: Unobstructed 150m_x000D_ RF Frequency: 433MHz_x000D_ Receiver Parameters_x000D_ Power Supply: AC110-230V _x000D_ Ringing Tone: 38 Songs (4 Adjustable Levels)_x000D_ Ringing Volume: 50DB / at 1m PackageList: 1 x Doorbell 1 x Receiver 1 x Sticker 1 x Instruction Note: Please supply power according to the voltage in use, use other voltages may cause fire and product damage!