Guitar String Action Gauge made of Aluminium in a Beech wood case.
The most reliable way of measuring the action of a guitar is to compare the height of the string to something of known height also sitting on the frets . This is best done visually without touching the string or the gauge. Our gauge is a thick aluminium sheet with steps milled into it that are 0.1mm lower each step - the steps are 5mm long. The steps provide a very accurate visual height reference that can be placed anywhere on the fretboard.
The gauge can rest on the guitar fretboard without to support it by hand - this means you can carefully and adjust the gauge position and carefully judge the action without having to hold anything in position. An advantage as then you cannot possibly change the string position by accidentally touching it.