- Monitors audio activity over a wide range of input voltages- Two sets of C-form (both N.O and N.C) relay contacts respond to audio activity- Four levels of signals: microphone 600-ohm line 25V and 70V speaker systems- Built-in balanced low noise high gain microphone pre-am- Transformer-isolated 600-ohm small signal level output of detected audio available- Works with self-amplified or central-amplified paging systems- Separate microphone pre-amp gain control- Adjustable release delay: 0.25s to 25s-