A Hydrostatic Release Unit is a pressure-activated mechanism. It is designed to automatically deploy a life raft under certain pressure. In case a vessel sinks, the HRU will activate and release the life raft at a depth between 1,5 and 4 meters. ioHammar Hydrostatic Release H20 for Life Rafts (USCG&EC Approved SOLAS) is a hydrostatic release unit designed to fit life rafts of all shapes and sizes (from 6 up to 150 persons). It is made of glass fiber reinforced nylon, which prevents it from corrosion