It is a multifunctional NMEA 2000 device with wires for connection of an external button with an LED indicator and a standard 4 or 8 Ohm sound speaker. It contains a 10W audio amplifier inside and a bank with 28 sound signals (car anti-theft alarm, ship horns, whistles, tone signals, etc.).
It can be used as a MOB button (emulates EPIRB with AIS VHF support), to sound digital switching events (acts as NMEA 2000 binary switch bank), or as an engine monitoring unit (sound engine alarms and can also be programmed to produce a sound alarm itself at a specified temperature, engine revolution reading, etc.).