Lollipop String Action Gauge Ruler Guide Setup Guitar Measuring Tool for Electric Bass and Acoustic Guitar With scale for string height, for ridge saddle slot depth and for nuts saddles and polepieces It's faster to use than any ruler, and stays parallel to the fingerboard-much easier than trying to hold a ruler perpendicular to a rounded fret The gauge features a progressive string height scale: simply slide it across the frets and read the measurement under the string Ruler size:8.9cmx5.1cm/3.5''x2.0''(LxW) Suitable for string instruments such as guitar, bass, mandolin, banjo, etc