Welcome to our factory, where we manufacture top-of-the-line communication systems. Our 4.3" Mechanical Pushbutton Indoor Unit Model B4 is one of our most popular products. This sleek and modern unit is designed to enhance communication and connectivity for homes, apartments, and offices. The B4 features crystal-clear audio and a user-friendly interface, making it easy to communicate with other units in the network. The pushbutton design ensures reliability and durability, and the compact size allows for convenient installation in any space. Our manufacturing process is quality-checked at every step to ensure that every unit is up to our high standards. Choose the B4 for reliable, intuitive communication.