The Nobels MS-4 is a MIDI program switcher that allows the user to send Program Change messages to control four external devices via four relay-switched outputs. When a MIDI Program Change is received, the MS-4 recalls one of its 384 stored switch combinations and changes the states of all four outputs accordingly. The unit features MIDI IN, MIDI THRU, and four MIDI-controlled relay outputs for switching amps, pedals, or other gear. A STORE switch captures and stores the current switch configuration to a program number. The MS-4 supports three banks of 128 programs and includes memory protect and reset-to-factory functions.