Altecnic Caleffi Pressure Reducing Valve, 15mm + Pressure Gauge Specially designed for hot and cold services in houses or apartments Equalizes the hot or cold water supplies or both Prevents excessive pressure at outlets such as taps and showers Specially shaped diaphragm to give accurate pressure regulation in response to changes in downstream pressure. The larger outlet chamber creates a low exit velocity which is effective in reducing water noise. The control stem housing of the cartridge is made from a plastic material with a low co-efficient of adhesion. Reduces scale deposits forming, the main cause of pressure reducing valve malfunction. .