52 SONG, 4 VOLUME LEVELS: This wireless doorbell has 52 melodic ringtones from around the world that can be changed with the press of a button. The product has four adjustable volumes (including silent mode), and also has a blue flash, and the silent flash mode is always on to meet your different needs. Range of 400 meters : Wireless signals can be transmitted within an ultra-long range of 400 meters (in open areas, the signal has good wall penetration capabilities, the signal can completely cover your house without interfering with other devices). . Memory function: This wireless doorbell automatically saves the ringtone and volume you set and automatically restarts after an unexpected power outage or when turned back on after being unplugged, eliminating the need for reset it according to your preferences. Waterproof and dustproof: It has IP44 waterproof and dustproof function, which can ensure the wireless doorbell can be used normally outdoors. The operating temperature range is -35°C to 65°C, achieving weather resistance, high quality and low power consumption. VERY EASY TO INSTALL: The signal receiver comes with a plug that plugs in and turns on, as well as double-sided tape and screws to hold the transmitter (button) where you want it. < p>The product does not include batteries. Note: The data is all measured manually, please allow 1-3cm error due to the difference in light and display, there may be have color differences, please refer to the actual item received.