These Inline Flow Metres are a convenient and economical way of measuring and setting the flow rate in a heating or plumbing system. These flow meters are made of brass and feature a viewing window which indicates the flow of water through them. The stainless steel screwdriver ball valve allows you to adjust and set the flowrate if required. The 1"MI x 3/4"FI model is calibrated to measure a flow of between 1 and 13 litres per minute, while the 1"MI x 1"MI model is calibrated to measure a flow of between 5 and 40 litres per minute. The valve can be installed in a horizontal, vertical or inclined position. Ensure that the arrow is pointing in the direction of the flow.