Fangrui Product Details Grooved Step Drill Bit: This Drill Bit Is Composed Of Industrial High-speed Steel And A Cobalt Coating, Possessing Durability And Strength. It Can Provide Outstanding Durability And Maintain Sharpness Even When Faced With Demanding Tasks. The Cobalt Coating Increases Wear Resistance And Minimizes Friction To A Great Extent. The Coated Step Drill Bits Are Highly Suitable For Quickly Drilling Holes In Aluminum, Wood, Copper, Stainless Steel, Plastic And Other Metal Sheets. Grooved Design: The Step Drill Bit For Metal Is Designed With Two-flute . Which Can Deburr Chips Faster And Smooth Drilling Holes.the Step Drill Bits Have 118 Split Point Tip, Which Can Accelerate Cutting Speed And While Preventing Angled Walking Away From Center. The Step Drill Will Long-lasting And Efficient. Wide Range Of Applications: This Step Drill Is Suitable For Drilling Holes In Various Types Of Sheet Metals Including Plastics, Aluminum, Wood, And Iron. (it Is Recommended To Add Coolant When Drilling Metal Sheets, And The Speed