The demonstration Manometer is designed to take water into a 'U' tube. It is 100x560mm WxH and fitted with a ring for hanging on a wall. The large 12mmD clear PVC hose is formed into a 'U' tube with a 400mmL scale mounted between the vertical legs. The ends of the PVC tubing protrudes from the top of the instrument so other tubes can be attached for gently blowing etc.. Can be used for measuring very small pressures (perhaps the pressure of natural gas) and demonstration of how such low pressures are measured in mm of water height.