【Excellent Design】433Mhz RF Self-generating Wireless Doorbell. You can install the doorbell receiver indoors and install the self-generating transmitter on your outdoor door, which allows your visitors to remotely ring your indoor doorbell via the outdoor door transmitter. Stable and reliable performance with high receiving sensitivity. Strong signal can pass through walls, floors, doors etc. The controlled range is about 200m. 【Easy to install】 The plug-in doorbell receiver can be plugged into any socket in your home. And the waterproof kinetic transmitter can be installed on the outdoor door. No wiring request. This kinetic transmitter has a built-in small generating electromagnetic coil. A small press on this transmitter can generate a current that powers it. No battery request. 【Wide application】 The products can be used in homes, farms, factories, offices, laboratories, supermarkets, etc. You will never miss a visitor.