Andoer Guitar Luthier Repair Tools Kit Set with Files Stainless Steel Ruler Winder String Action Gauge Three double-edge nut files, with 6 different specs, the set of three files does the work of six. One stainless steel ruler, used at the bottom while nut slotting, act as the nut slotting depth benchmark, also to prevent scratches finish. A sheet of string action ruler with centimeter and inches unit on side can quickly find the right distance and measure the accurate string height. One special string winder, help to replace your strings in seconds with this classic winder. Main Material: Stainless Steel & Steel