Perrin & Rowe thermostatic showers feature valves that have two handles. One handle controls the temperature while the other controls the volume. Unlike a pressure balance shower, a thermostatic shower valves react to the temperature rather than the pressure of the water. With this type of shower, you can change the flow volume without affecting the temperature which is beneficial for conservation when shampooing, or shaving, as an example. Whether your showering preference is a gentle, relaxing rainfall or a rejuvenating cascade of water, a Perrin & Rowe shower can accommodate your every desire. Our wide array of fine showerheads, body sprays, valves and accessories give you the freedom to check off every item on your wish list. Trim plate and temperature control for U.5585BO or R1085BO thermostatic rough valve Includes driver piece 9.21207 required to operate Order U.3157 for the 1 1/4" extention kit Temperature control includes pre-set safety stop with override Must order U.5585BO or R1085BO rough valve to complete