The string height measurement method is very simple: Bottom of string at 12th fret meets the top of the line.Fret rocker, String height gauge, and slot depth measurement all in one, Stop pay more for fragmented tools.Product Features:-Made of high hardness stainless steel, Handles any rough movements and drops.-With 4 lengths edge, easily span any three adjacent frets.-Every contact edge is very straight and smooth. If abnormal wobble is perceived, that is where the buzzing fret located, rather than the uncertainty that a product with jagged edges gives you.-The markings are etched by a high-precision laser and then manually colored for a permanent presence.-Each side of edge is finely chamfered, refusing any sharpness, refusing any scratches.-The 1mm thickness completely negates the disadvantage of paper-thin and easy-to-bend, This is why it can only be inserted into slots with a width greater than 1mm,such as bridge slot.-Elegant black plating avoids mirror reflections, which you don't want to encounter. The white marks make reading clear and is necessary for people with poor eyesight.-Accurate graduations is necessary for accurate measurement of string height, and the error of the graduations is always kept within 0.05mm(1/5 of the hair diameter).-Metric,imperial,64th marking all in one, which is very useful for people not skilled in metric/imperial conversion.-Compared to other similar products, we removed one graduation(0.25mm/0.01in) that was useless for all stringed instruments and added two graduations(3.75~4mm/0.15~0.16in).Why? While the low string height brings a comfortable feel, it also loses sound quality. For classical guitars, 3.75~4mm(0.15~0.16in) is still an option.These two graduations will bring more possibilities for classical guitars.Package Contents:Vencetmat String Action Gauge & Fret Rocker x 1.