The Monument 1515U Water Flow Weir Gauge is designed to measure water flow rates in order to determine if suitable flow is available in a building prior to the plumbing installation of washing machines boilers showers etc This type of water flow gauge is also used for diagnosing if a combi boiler or water heater may need de-scaling The water flow gauge is made from durable plastic with a stainless steel mesh strainer to avoid turbulence It features a dual scale to measure flow rates of 2 to 25 litres and 1 to 5 gallons per minute