The Apart E-VOL20 is a 100 volt volume control. It can handle up to 20 watts of power and is very durable thanks to the step-by-step attenuation in 11 steps + zero position. The E-VOL20 is designed to handle 24V priority signals. This means that you can always get an announcement out, even to zones where the local volume control is in the ‘OFF’ position!If your amplifier has a 24V priority output, it will send a 24V signal when you push the talk button on the microphone. The 24V signal will close a relay on the E-VOL20 volume control, and the signal will pass, even when the volume control is in the ‘OFF’ position. This can be very useful for emergency or evacuation messages. The E-VOL20 is built on a universal chassis that easily can be integrated with Gira, Jung and Euro.