Bosch offers a full range of sound volume controllers and sound source selectors for a complete public broadcast solution. Basic function operating public broadcast systems are commonly used for information and background music propagation. The volume controller can be used to adjust the volume level locally. In addition to the volume controller, you can install a sound source selector so that you can select 5 different sound sources locally. When broadcasting is required, the built-in relay ensures that the signal is broadcast at a preset volume level, independent of the local volume setting. According to the rated power, the volume controller provides three models: 12 W, 36 W and 100 W. The total load of the loudspeaker connected by the volume controller shall not exceed the rated power. In addition, all three models are available in the following two versions. One is the power-saving 4-wire volume cover version (model /10), which activates the cover relay in the event of an emergency call. The other is the fail-safe 4-wire volume overwrite version (/20), which unactivates the overwrite relay in the event of an emergency call. The design and color of the volume controller is perfect for any indoor environment. In addition, the design process is also optimized for ease of installation, ease of operation and reliability. Interconnect component screw connection certificate and approved safety in accordance with EN 60065 standard flame retardant UL 94 V0 standard