Quarter-round concave filing surfaces are at each edge of this unique fret file. The smooth flat underside minimizes fretboard marring while rounding the fret ends.  Each smooth-cut filing surface is 4-1/2" long and extends approximately .080" above the fretboard. The file is 3/8" wide, and is fitted with a turned hardwood handle and brass ferrule. Works on stainless frets, too! All of our tools are suitable for use on stainless-steel fretwire, with the exception of our Fret Tang Nippers and Fret Cutters. Modern stainless-steel fretwire is known to be harder than the traditional nickel-silver blends, but our own shop experience indicates the wire does not cause premature wear of files or sandpapers.