Feature: Material: Tungsten carbide,high speed steel,wear-resistant & durable. Shank: 1/8 inch(3mm),Length:8/5 inch(40mm). The Carbide Rotary Files can work with most small rotary tools (like Dremel tool), perfect for processing all kinds of materials such as wood, plastic,foam or resin models 20 different tools, include: rotary burrs, grinding head and rotary burr cutting tools etc,meet most of your drilling needs,suitable for engraving, beveling, chamfering, grooving, reaming, hollow. Speed is generally 6000-50000 rev / min,long service life, reduce the inefficiency turnover,stay sharp longer. Uses: 1.Micro-drilling or cutting portion provided in various forms. 2.Length of the material efficiently handle around 39mm. 3.20PC set of Grinding Routing Bits Including Mandrel. 4.All with fitted 3mm diameter mandrels will fit most rotary tools including Dremel. 5.These 20 HSS Routing Bits are perfect for all sorts off jobs like Model making and the like. 6.Purpose: stone carving, jade carving, grinding, polishing Material: Other-- includes:20 x HSS Routing Wood Rotary Drill Bits