Abstract: The present invention is a gauge for selecting musical instrument strings. It includes a base member and at least one movable member that is engaged to the base member, and which provides information related to specific musical strings. In preferred embodiments, musical string information is written onto the base member and the movable members contain viewing windows that display the information. A separate movable member is provided for each string of a string set. In the preferred embodiment, the base member and movable members are shaped as crcular disks and they are rotatably joined about a common centrally disposed axle.