Made from stainless steel , sturdy and , and wear-resistant, not easily damaged. Fingerboard Polishing Gasket protect your guitar or bass fretboard frets from or damaging while filing and polishing. String Height Gauge ruler with precisions etched markings, will not easily wear off from continued use. Suitable for measure string instruments such as electric guitar, electric bass, acoustic guitar, acoustic guitar, electric box guitar fretboard measured. Accurate, convenient, pocket-sized measuring tool can be taken to everywhere you like.