The SZ-310AR with Mounting holder is a sound unit manufactured by Patlite and designed for a wide range of audible voice warning applications. It features a built-in speaker, acoustic buzzer, constant tone, and programmable alarm sound, as well as both an output volume and tone control. It is made from durable, impact-resistant ABS plastic, and its mounting holder is designed to enable easy installation. This sound unit can be used in many industrial settings such as airports, railway stations, and other transportation systems, as well as other types of personal or industrial audio applications.