[Self-generation]: No need for batteries, cables or other power sources, just press to automatically generate power and ring the bell; eco-friendly, save money and worry-free. Receiver is a standard French plug [Waterproof design]: Not afraid of rain and sunshine to ensure product quality stability without unnecessary worries [Signal stability]: The wireless transmission range of 100 meters enables use in any scene, whether single or multi-story [Multifunction]: It can be combined with 1+N or N+1 to meet different needs; It can be used as a caller for the elderly, pregnant women, patients and other disabled people, suitable for families, homes Pensions and Hospitals [There is no such thing as perfection in the world]: If you find the product has any quality problems, please contact us first, we will solve the problem for you until you are satisfied