[HSS titanium coated bit set] High speed steel and titanium coating durability and , reduce friction and make operation cooler. [Ultra automatic center drilling] Do you know that when you try to drill into metal or hard surface, no matter how stable you it is, the drill will ""? Yes, we have a tool. The automatic center punch has a heavy spring effect. You only need to place the tip where you to drill, and it will make a slight indentation on the surface. Enough to keep the drill bit from moving [118 separation point] These step drills have a small angle of 118 , which can the cutting speed and prevent the inclined walking from the center. Double groove design provides smoother cutting and removal [Double groove and three flat bits] These bits have double groove straight design, performance and durability. The of these step drills has three planes, which help prevent the drill bit from sliding in the drill chuck during drilling [Drill holes of different sizes] The bit set includes 5 standard bits, which can replace 50 individual bits. 6-step drill (3/16 inch to 1/2 inch), 9-step drill (1/4 inch to 3/4 inch), 10-step drill (3/4 inch to 1-3/8 inch), 12-step drill (1/16 inch to 7/8 inch), 13-step drill (1/8 inch to 1/2 inch). High-quality metal drill for metal, wood and plastic plate. Suitable for family DIY, miscellaneous workers and Material: high speed steel colour: gold Package Contents: 1 set x Step Drill Bit Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the a little different from the real thing. The measurement allowed error is +/- 1-3cm.