This rule removes the guesswork from laying out frets. It is accurately marked with fret spacings for steel-string and classical guitars, as well as with standard Imperial and metric graduations (in 32nds and millimetres).
It has 25 11/32" and 24 27/32" scales (Martin long and short scales) for steel-string guitars, as well as 25 21/32" (standard) and 26 1/8" (Spanish long pattern) scales for classical guitars.
It also has diagrams to help with even string spacing on four different nut widths (including one for 12-string guitars).
Made of 1mm thick stainless steel with a matte finish and etched and black-filled markings, the rule is 1 3/8" wide and 28" long overall.