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 power outlet to get started. What's in the box: 1 x transmitter, 1 x receiver, 1 x double-sided sticker, 2 x screws, 1 x Installation guide user. Note: Due to the light and screen setting difference, the item's color may be slightly different from the pictures. Please allow slight dimension difference due to different manual measurement.