It is a distress transmitter whose purpose is to signal the position of boats and ships in serious emergency situations.
It essentially consists of a radio transmitter that interfaces with the satellite system for search and rescue operations.
When in use, the EPIRB emits signals on emergency frequencies that are picked up by the network of satellites in orbit and transmitted back to the ground at the rescue coordination centres.
The correct procedure for activating the EPIRB is as follows: