Wide range of uses: height ruler helps to measure slot, string height, nut and pickup pole piece, and even slot depth. The notched ruler helps to check whether each fretboard is at the same level, and the fret rocker can span 3 frets and check whether the frets are at the same level. Keep the guitar neck straight: Guitar ruler, string leveling tool and guitar string ruler can help you measure whether the fretboard is straight and check the final height after you readjust or replace the fretboard. Anti-rust material: rocker and notched ruler are made of stainless steel, which is and can be used for a long time, and it is not easy to scratch the guitar. gift: These guitar luthier tools are excellent gifts for guitar technicians and guitarists, helping them to maintain and repair instruments by themselves in a short time and reduce buzzing; suitable for electric guitars, acoustic guitars, basses, banjos and folk guitars, etc.