EASY TO INSTALL: Includes 2 transmitters, 4 screws, 4 dowels, 1 key, and 2 double-sided adhesive strips for flexible wall mounting. Wireless setup allows for quick and simple installation. EXTRA LONG WIRELESS RANGE: Up to 400 meters (1,300 feet) in open areas without interference. Ensures reliable signal coverage throughout your home, even across multiple floors or rooms. 52 TONES AVAILABLE: Features a 40mm stereo speaker that delivers clear, rich sound. Offers 52 selectable melodies and 5 adjustable volume levels, with a maximum output of 115 dB. Assign different chimes to each transmitter to identify which door is being used. HIGH-PERFORMANCE TRANSMITTER: Designed for efficiency with very low power consumption. Powered by a CR2032 lithium battery, lasting up to 3 years. Built with dust resistance and IP55-rated waterproof protection. Operates reliably in temperatures from -20°C to 60°C, suitable for various weather conditions. MEMORY FUNCTION: Automatically retains the last selected chime and volume settings after power interruptions. No need to reconfigure the device, ensuring consistent performance and ease of use.