Jiayouy 11 Pieces Guitar Luthier Tool Kit Including 9Pcs Understring Radius Specifications: The guitar measuring tools are made of stainless steel with smooth edges that have no burrs, anti-rust and scratch-prevent, durable and long service life. String action gauge : comes in 9 x 5.1 cm/ 3.5 x 2 inch, metric imperial. etch printing on double sides, will not fade, accurate and clear to measure string height, bridge height, nut slot depth, bridge slot depth and pickup height. 32 Blades Feeler Gauge measuring range: 0.0015 inch/ 0.04 mm to 0.035 inch/ 0.88 mm, can be applied for guitar spacing distance measuring.Warm notice: there is some anti-rust oil on the stainless steel feeler gauge to prevent it from rusty, please don't worry about that. 9 Understring Radius Gauge including: 7.25", 9.5", 10", 12", 14", 15", 16", 17" and 20" radius can be applied to measure fret board radius, saddle radius, nut radius from either the top or the bottom radius surface. Make the necessary measurements and adjustments on acoustic and electric guitar, bass, banjo, mandolin and other stringed instruments.