Wireless Doorbell – Battery-Free Design Battery-Free Operation: Uses unique PUSH-RF technology, converting kinetic energy into an electrical signal to ring the doorbell wirelessly. No more battery worries! 45 Melodies & Adjustable Volume: Offers 45 classic melodies with adjustable volume (0dB to 90dB), ensuring audibility for everyone. A visual LED indicator is also included. IP44 Waterproof: Weatherproof design (IP44) made from safe and recyclable ABS material. Operates in temperatures from -20℃ to 65℃, withstanding sun, rain, snow, and frost. Long Wireless Range: Boasts a wireless range of 150M/500FT, ensuring you never miss a visitor, even in large homes or across floors. Two plug-in receivers are included. Easy Installation: Simple and user-friendly design. Use the included double-sided tape or screws to mount the doorbell button. Plug the receiver into an outlet.