The H20 keeps the raft safely lashed on deck, until a vessel goes down and a controlled embarkation to life raft was not possible. Then the H20 releases and activates the inflatable life raft. See What it does here -SOLAS approved -Activates at 1,5-4m -Also for rafts more than 25 persons -2 years life time from installation dateThe Hammar H20 is a hydrostatic release unit designed to fit life rafts of all shapes and sizes. It is made of glass fibre reinforced nylon, which prevents it from corroding. The Hammar H20 requires no annual service, maintenance or spare parts. Simply install a new one every two years and dispose of the old one. With the environment in mind, the old unit is 97% recyclable. The Hammar H20's solid white rope is attached to the deck or cradle of the liferaft and secured to the liferaft lashing with a sliding hook. If the vessel sinks, the water pressure will activate the sharp knife that cuts the rope within 4 metres and the liferaft will float free. As the vessel sinks, the liferaft line will be stretched and the liferaft will begin to inflate. The Red Weak Link will break and survivors can safely board the floating liferaft. -SOLAS approved -Active at 1.5-4m -Also for liferafts with more than 25 people -2 year lifespan from date of installation.