Believe us! It is an indispensable tool both for guitar technicians and guitar players! This luthier tool set is designed to help with the common repairs and adjustments of guitar fretStainless Steel Feeler Gauge Instructions: 1. Ensure that the feeler is clean 2. Insert the feeler gauge into the gap to be measured, adjust it, and tighten the screw when you feel a little resistance. At this time, it is the measured data. Material: 65 manganese steel with a lube oil coating to prevent pitting and corrosion. Blades: 32 pieces Measurement: from 0.0015 inch (0.038 mm) to 0.035 inch (0.889 mm)Radius Gauge Radius Gauge come in the most popular fingerboard radius and make it easy to measure the radius from either above or below the strings Material: Stainless steel Radian Measurement: 7.25", 9.5", 10", 12", 14", 15", 16", 17" and 20" radiusString Action Ruler Material: stainless steel Size: 55mm×90mm×1mm Graduations displayed: mm and inchesFingerboard Guards: Material: stainless steel Size: 3 x 0.8 inch and 3 x 0.5 inch Designed to protect the fingerboard when doing work on your fret. Prevents scratching or damaging to guitar or bass fretboard when filing and polishing frets.Grinding Stone: Size: 3.9 x 0.4 inch/ 10 x 1.1 cm Professional tool for polishing saddle, nut and frets All accessories are placed in a bundle pocket, easy to store and carryPackage Including 1 Set of 32 blades feeler gauge 1 Set of 9 understring radius gauge 1 Set of string action ruler 2 x Fingerboard guards 1 x Grinding stone