High-quality T-shaped radius gauge set for accurately measuring and adjusting guitar fretboard radius and string height. Includes 9 precision stainless steel gauges with common fingerboard radii: 7.25", 9.5", 10", 12", 14", 15", 16", 17", and 20". Use the bottom edge to measure the fretboard radius and the corresponding top edge to set saddle height for optimal string alignment. Ruler side allows adjustment of string action on electric, acoustic, classical, and six-string guitars. Ideal for luthiers, guitar technicians, and players for quick setup and maintenance to reduce string buzzing. Durable silver-finished stainless steel construction. Package includes 9 T-shaped radius gauges and 1 string height ruler. Colors and measurements may vary slightly due to lighting and display differences. Allowable measurement error: +/- 1–3 cm.