The practical Solight Wireless Doorbell, 250m, White, Learning Code (1L53) doorbell can be used at home or at the office. The bell features 58 ringtones. The bell has a range of up to 250 m, meaning you can safely place it on a remote entrance gate. The bell requires a permanent mains power supply to work. This is fine if you don't need the bell to be mobile. The bell needs batteries for its operation, which you will use mainly if you plan to move the bell within the house. Audio transmission takes place over radio waves.