Hosco Japan Zone File under-string fret rocker and diamond file 50x30x10mm

The Zone File is a unique tool that allows you to check the fret level while the strings are on and, if necessary, make adjustments with the diamond file on the fly. To cover the zone from the low fret to the high fret, four lengths were needed. For this reason the Zone files were designed in a trapezoidal shape; two files make one full set.

The name "Zone File" is derived from its unique "Z" shape. Its purpose is to check and adjust a specific zone of three adjacent frets. The edge of the "Z" is used as a straight edge gauge to check fret height, and the diamond file in the centre of the "Z" flat surface is to adjust the fret height.

You can check the fret level while strings are on! Set the Zone file so that it passes under the strings to be checked. Select a zone file that is long enough to span the three frets to be checked. Tilt the zone file so that its edges touch the three frets, and check with both hands to see if there is any rattling. If there is no rattling, move the file by one fret and continue the check in the same manner.

If you find a high fret, you can also adjust the fret level with the strings on. If there is any sagging, it means that the centre fret is high. So set the Zone file so that the diamond file surface touches the fret, and gradually polish to adjust it. As soon as the fret is levelled correctly, depending on the amount of height reduction of the fret it might be necessary to remove the strings and reshape the fret crown with a crown file.

Size: (ZONE-L) 105 /75 (l) x 30 (h) x 10 (w) mm / (ZONE-H) 50 /35 (l) x 30 (h) x 10 (w) mm
Diamond file : #800 grit, (ZONE-L) 15x8mm + 15x8mm / (ZONE-H) 12x8mm + 10x8mm
Material : stainless steel, 1mm thick