Replacement Pressure Balancing UnitThis replacement pressure balancing unit is a genuine American Standard part designed for use with UltraMix pressure balancing bath and shower with built in diverter, 1321 series, 1325 series, 1351 series, 1354 series, 1355 series. The unit maintains constant output temperature in response to changes in hot and cold supply pressure. Its diaphragm system is engineered to eliminate cross flow. This unit avoids failure due to mineral deposits, making it