PWT® Controllers The nerve center of our PWT® offering. Modular, pre-programmed units. MCR-115 MICRO Plumb Products Single Shower Control. Electronic shower control used with the MICRO Plumb push buttons and solenoids to control a single shower. MCR-4011-A PWT 4-I/O Communicating Controller MCR-4014-A PWT Products 4-I/O Control Module MCR-8012-A PWT Products 8-I/O Control Module