The Ocean Signal SafeSea HR1E HRU is a replacement Hydrostatic Release Unit for the Ocean Signal ARH100 Automatic Release Housing. This works by ensuring that the EPIRB is released from its bracket when submerged in water. Once this is released, the EPIRB is activated, sending a distress signal to the relevant authorities. The metal pins in the sides of the EPIRB activate when submerged, creating a circuit which sends of the distress signals. This is suitable for the Ocean Signal EPIRB 1 Pro and the E100G. Key features: Suitable for Ocean Signal EPIRB1 Pro and E100G Ensures release of EPIRB in the event of an emergency.