The signature feature of Micro-Frets guitars was not in the fretwork, as the name would suggest, but in the nut – or to be technically correct, the six individually adjustable nuts that were intended to provide better intonation.

The segmented, adjustable nut was one of three innovative features developed by Ralph Jones of Frederick, MD, who founded the company with financial backer Marion Huggins in 1967. Early models featured a body with a routed top and routed back that were joined at the sides. Within a year he had introduced the Calibrato, a vibrato designed to provide better intonation by taking into account the differences in string gauges.

The bodies of Micro-Frets models typically had a modern element, like the pointed horns of this 1968 Signature, but with a body that looked a little overweight. And the micro-nut adjustment looked more useful than it actually was; it affected only the interval between the open string and the string played at the first fret.

Jones died in 1973, and Micro-Frets guitars were gone within a year.