Manufacturer: Absdefen [High Sensitivity Receiver] This doorbell uses a high-sensitivity receiver and has a range of up to 300m. The sensor sensitivity can be adjusted to meet your needs. Low sensitivity induction distance: 5-8 M, Medium sensitivity induction distance: 8-12 M, High sensitivity induction distance: 13-16 M. The transmitter can be fixed in place with screws. The receiver plugs into an outlet. With a high-sensitivity receiver, it can stably receive signals through walls, wooden doors, steel doors, etc., and can be used in two-story buildings. [38 Ringtone Selection & Volume Adjustment] You can choose from 38 different chime sounds and adjust the volume. The volume adjustment function allows you to lower the volume at night to avoid disturbing neighbors. There are 38 melodies in total, so you can choose a different song every day. The music plays simultaneously with the LED indicator light. [Solar Charging & Long Operating Time] When the button is turned on, it will automatically fully charge during the day. After a full charge, it can be used for 30 days in standby mode. [Expandable Function] One human sensor receiver can be paired with up to 30 transmitters (chime side). The receiver can be paired with up to 30 ringtones. By adding a new receiver, you can also pair it with various chimes. For example, it can be used in villas, hospitals, office buildings, etc., for the care of patients, detection of visitors, and theft prevention. [Store Helper, Welcome to Customers] Wireless human sensor chime: When a person comes directly under the door or entrance, the wireless human sensor chime can play a welcome tone and welcome song, giving customers a pleasant feeling. It has a motion detection function that can accurately detect visitors, with a detection angle of 15° up and down and 100° left and right.