MusicNomad U FILE for Leveling Single Guitar FretsDesigned by our Sonoma, CA team, the innovative U File lowers single high guitar frets, effectively eliminating string fret buzz. Our unique U shaped channel design slides under the string for optimal file placement and uses a wide diamond coated file to quickly and efficiently lower and level the fret height to match adjacent frets. With strings on or off, lay across 3 frets with the high fret in the middle and file either up or down or side to side.