Stepped Countersink Drill Bit, Double Slotted Tapered Countersink Step Drill Bit (Perfect Size: For precise drilling of different sizes of 5-35mm in diameter, a drill can handle holes of different sizes.^ High Quality Material: The titanium alloy coating is made of high quality HSS, which can ensure extremely high durability and reduce friction and heat. Titanium alloy drill bits are especially suitable for processing thin copper and aluminum parts / iron plates / wood panels / plastic plates and other thin plate materials.^ Easy to Drill: The position of the marking hole and double flute design make drilling faster and smoother, as well as precise drilling.^ Laser size: The dimensions are laser engraved into the metal so that they do not wear out even after repeated use.^ Applicable materials: plastic, wood, copper, iron fiberglass, PVC, metal fin and aluminum 3mm