There are different types of emergency beacons, the ones who refer to a vessel and the one who are personally registered.
The Search and Rescue Transponder (SART) and the Emergency Position-indicating Radio Beacon (EPIRB) are the two beacons that er mandatory for all commercial vessels.
Personal locator beacons
ACR has two types of PLBs, one with GPS tracking and one with AIS and GPS technology. The AIS PLB sends an alert message within seconds to all local vessels with an AIS receiver and/or AIS-enabled plotter. The GPS PLB quickly and accurately relays you position to a worldwide network of search and rescue satellites.