It can detect the curvature of the guitar neck without removing fret, directly measure the flatness of the guitar neck with fret, accurately judge the degree of local deformation of fingerboard/guitar neck, and two groups of notches on both sides are suitable for fret positioning of most common Specifications. Features: The easiest way to check your fretboard's flatness. Dual scale, suitable for fret positioning of most common Specifications. This straight edge is machined from stainless steel of years of dependable use. Essential for proper truss rod adjustment. There are 21 notched on one edge and 22 on the other edge. Specifications: Material: stainless steel Color: sliver Item size: 420 * 37 * 3.5mm / 16.5 * 1.5 * 0.1in Package size: 420 * 37 * 3.5mm / 16.5 * 1.5 * 0.1in Package weight: 217g Package List: 1 * Guitar Neck Notched Ruler