The String Action Gauge has a variety of ruler markings for taking a variety of measurements across the guitar indispensable for set up work.

Along the bottom edge is a progressive scale that goes up in 0.25 mm increments up to 3.5 mm (metric version) or 0.01" increments up to 0.14" (imperial version) for easily reading and setting string action height, the ruler will span multiple frets ensuring it stays flat and perpendicular to the fret, much easier to use than a traditional ruler. Along 1 narrow end is a depth gauge for for checking saddle, nut and fret slot depths as well as pickup, nut and saddle heights. Along the other narrow end is right hand and left hand ruler measuring inwards towards the centre of the ruler for checking string and pole piece spacing, and there is a traditional ruler along the top long edge.