A set of 26 steel gauges designed for luthiers is especially very useful to allow the precision filing of nut slot depths.Simply stack the appropriate gauges on the fingerboard, against the front edge of the string nut, and file the nut slot down to the top of the stack.This gauge set holds the most popular and common sizes with thicknesses ranging from 0.0015" to 0.025" (in inches).All thicknesses are measured in the metric and imperial systems and sizes are marked on each blade for easy identification.Each gauge set comes assembled in a U-shaped metal holder to protect the blades when not in use.The user can "fan" out the blades for easy selection, and then return the unused gauges back into the holder.The screw and locknut can be tightened to secure the blades in a working position.Thicknesses range: 0.0015", 0.002", 0.0025", 0.003", 0.004", 0.005", 0.006", 0.007", 0.008", 0.009", 0.010", 0.011", 0.012", 0.013", 0.014", 0.015", 0.016", 0.017", 0.018", 0.019", 0.020", 0.021", 0.022", 0.023", 0.024", 0.025"