Description:  【Guitar Fret Leveling Sanding Beam】The Aluminum Fret Understring Leveler is a tool for guitarists and luthiers, allowing you to perfectly level your frets without removing strings. 【DURABLE MATERIAL】 Guitar fretboard sanding tool made from high quality aluminum that is CNC machined and treated with an excellent oxidized sandblasting process, ensuring durability and resistance to deformation. 【MULTIPLE USES】 Guitar sanding block suitable for sanding electric guitar, acoustic guitar, electric bass, banjo, mandolin, and other string instruments. Perfect for leveling frets, fingerboards, and fret crowns, making it a versatile accessory for both performers and luthiers. 【file bar】 The 4.5" (114mm) length is ideal for spot leveling of the frets across the entire neck. It's also great for creating backs on acoustic guitar. 9" long (228mm) designed for smaller necks like ukuleles and mandolins. It is also suitable for leveling diatonic necks and spot leveling. 18" long (457mm) allows easy leveling of the entire neck. 【PRECISE DESIGN】The precise guitar leveling bar surface works quickly and accurately with open or closed strings so your fret stays level. Each leveling job receives its own file bar. Size Chart: 11.4cmx3.8cm/4.49inchx1.50inch 22.8cmx3.8cm/8.98inchx1.50inch 35cmx3.8cm/13.78inchx1.50inch 45.7cmx3.8cm/17.99inchx1.50inch Package Includes: 1 Aluminum file bar Understring Leveler(Size optional) Note: Please allow slightly errors due to manual measurement and different monitors.