String Instruments Accessories -String Action Radius Gauge Ruler Guide Tuning Measure Tool Luthier R20 Highlights Generic Brand String Action Radius Gauge Ruler Guide Tuning Measure Tool Luthier R20 Description: Guitar Tuning Tool Stainless Steel String Tool gauge Luthier High quality and durable in use Designed for string instruments, such as guitar, bass, mandolin, banjo, etc. Great for luthiers, guitar lovers and DIY for many other frets Material: Stainless Steel Size Chart: Lx W: Approx. 79x79mm / 3.11x3.11inch Package includes: 1x String Action Gauge Ruler Note: Due to the difference between different monitors, the picture may not reflect the actual color of the item. Due to manual measurement, there may be an error of 1-2mm.