The price shown here is for a waterblock device, reset device, pressure reduce and ball valve. The Water-Block(tm) Flood prevention device is desgined for washing machines, dishwashers, water coolers etc as a means to prevent flooding in the event of failiure of the machine. In a domestic situation this could be an event such as a split drum on a washing machine, but more commonly we supply these for water coolers, where risks are usually physical (i.e. someone knocking it over or vandalising the equipment). If your machine is connected at regular mains flow, you would probably be looking at losing 11 to 15litres per minute if a flood occurred, which in a domestic or office situation could cause a devastating flood.