1. The discs are super-thin making them perfect for making slots and and coated on both sides as well as around the edge 2. Diamond burrs Excellent for fine detail work, cutting, engraving, carving, touch-up and finishing,Work on glass, metal , stone, ceramic, wood, plastic 3. Processing of metallic and Non-metallic surfaces using an engraving machine or mini-Drill forms of cutting part provide efficient processing of materials length is about 40mm,Shank Diameter is 3.17mm 4. Compatible with most of rotary tools (/ Menards Roto/ / Fordom, Etc) used in hardware, hobby, home, etc Maximum RPM: 20,000 Name:Engraving Accessories Set colour:Silver material:High speed steel + diamond Package Contents: 6x circular saw blades (22mm, 25mm, 32mm, 35mm, 44mm, 50mm) 30x diamond grinding needle 6x rotary file 1x connecting shaft 2x chuck Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.