Self-powered wireless doorbell: no battery, no wiring; no batteries; easy to install, and very eco-friendly. Long range: Maximum range of 200 meters in the open area without obstacles, the effective distance at 3 volume levels allows you to hear the ringtone and respond in time to the door. The appearance is simple and compact, and this device can also be used as a beeper (sound signaling), and is suitable for the elderly, children, etc. The wireless and battery-free doorbell has 38 different chimes and 3 adjustable levels to meet your needs. Easy to install and use: The transmitter can be used with 2 types of installation. Use the included tape or screw to secure the transmitter to the door frame. And the doorbell receiver in the socket to start. Box contents: 1 x transmitter, 1 x receiver