The MS-4R provides the ability to control one projection screen from multiple locations using the motor?s voltage (110V or 220V). MS-3R and MS-4R are 3- and 4-wire versions of the same switch. For multiple control stations, either 3- or 4-wire versions of the MS-4R are utilized. The MS-4R is the first control station and also the intermediate control(s), with the MS-3R being the last control station in the series. Automatic override allows only one signal to reach the motor when switches are operated simultaneously. Not intended for use with any other controls.