Bosch PVA-1WEOL End-of-line supervision module, Module for monitoring the loudspeaker line for short and open circuits. Compatible with 100V, 70V, or 50V loudspeaker lines, Module is powered via loudspeaker line (pilot tone), A single loudspeaker line can have multiple modules, Up to 60 modules can be connected to one amplifier output channel, EN 54-16 system certification.