Brand Name: American Standard;Product Type: Pressure Balancing Unit;Fits For: American Standard;Function: Tub and Shower;Diaphragm system engineered to eliminate cross flow;Maintains constant output temperature in response to changes in relative hot and cold supply pressure;Ideal for use in hard water;Avoids failure due to mineral deposits;Easy to install;Use with following American Standard tub/shower and shower only controls:;Ace No. 4398681 (9316502.002);Ace No. 4398699 (9316502.295);Ace No. 4398673 (9316501.002);Ace No. 4398517 (9046502.00);Material: Plastic; This pressure balancing unit maintains a constant output in response to changes in the hot and cold water supply pressure. This reduces the chance youll experience dramatic changes in water temperature in the shower. The diaphragm system with integrated check valves is engineered to eliminate cross flow and this Pressure Balance Unit is also designed to avoid failure due to mineral deposits so it is ideal for use in hard water areas. This pressure balance protects against scalding and is for use with American Standard R110 R120 R115 R125 rough in valves.