Abstract: A fretted stringed musical instrument is provided with channels which can removably accommodate frets. In a preferred embodiment of the invention, the channels are provided at locations where it is sometimes, but not always, desirable to have a fret. The frets which are standard to the instrument may remain imbedded in the fingerboard. Alternatively, channels may be provided at all possible fret locations such that the instrument can be played fretted or unfretted. This embodiment would eliminate the need for expensive, time consuming, and instrument damaging refretting operations. In another embodiment of the invention, a set of tempered frets can be used to change the temperament of the instrument, such as from equal temperament to mean temperament in an Appalachian dulcimer. In another embodiment, using frets having a variety of lengths, it also becomes possible to fret only certain strings.