The HydroFix Hydrostatic Release Unit (HRU) is a patented rod system that allows a beacon to be quickly and reliably released from a Category I bracket when submerged in water between 1.5-4 meters (4.9-13.1 feet). This unit is designed to work with the Sea Shelter, Sea Shelter2, Sea Shelter3, and Sea Shelter4 beacon brackets. Note: This date-stamped product must be replaced every 2 years from the date of installation or 4 years from the date of manufacture.