High-quality material: this guitar radius messenger is made of high-quality stainless steel, with good hardness, corrosion resistance, no rust, smooth and round edges, durability and long service life. Size: This radius messenger for guitar set contains nine sizes with radii of 7.25, 9.5, 10, 12, 14, 15, 16, 17 and 20, which are rich in quantity and different in size and can meet your different usage needs. Easy and precision: this under-string radius gauge has clear labels on the surface and is easy to measure and read data. It can be used to accurately measure the radius of the upper radius or the lower radius of the bundle plate and the saddle. Lightweight and practical: this guitar measuring tool is small and light, only the size of a bag. You can put it in a bag, bag, drawer, etc. and you can carry it anywhere you want. Wide range of applications: this radius string messenger has a wide range of applications and can be used to measure various electric guitars, electric bass, acoustic guitar, electric guitar keybow measurement and curvature adjustment string bridge.