58 Melodies 5 Volumes: The doorbell receiver has 58 chimes and 5 adjustable volume levels (0dB-100dB) to meet your needs in different occasions. Press the "Next" or "Previous" button to easily select from 58 melodies. High-Performance Transmitter: Ultra-low power consumption; the doorbell is powered by USB and the button uses a CR2032 lithium battery with a maximum service life of 3 years. IP55 Waterproof Doorbell: The doorbell button body is designed for outdoor use. Out. Outdoor, also suitable for all weather conditions. IP55 dust and water resistance; operating temperature range is -4F to 140F; withstands all kinds of harsh weather conditions. Memory Function: Remember the last melody and volume after power failure; no need to reset the previous settings; convenient and easy-to-use design, enhance user experience. 200M Open Area Operation: The wireless doorbell signal can easily pass through doors or metal walls, ensuring that you never miss visitors, even if Function Multiple connection combinations Configuration according to the size of the environment The number of transmitters and receivers should not exceed 20. 1. USB powered, can be positioned arbitrarily. Suitable for global use. 2. 4 unique mode functions: flash only without sound, sound only without flash, strong flash, constant flash. 3. IP55 waterproof button, built-in waterproof rubber band, truly waterproof. 4. The button comes with a label cover where you can put the house number and other reminders. 5. Add the function of distinguishing the front and rear doors, press different buttons, and the receiver will play different music. 6. The sound quality is clear and clean, without noise, and pleasant to the ears.