Specification Shank: 1/4" Quick Change Hex Shank Finish: Titanium Material: HSS Size: M(5 Steps)/ L(9 Steps)/ XL(15 Steps) optional Measurement: 4-12 5 Steps (Diameter 4, 6, 8, 10, 12mm) 4-20 9 Steps (Diameter 4, 6, 8, 10, 12, 14, 16, 18, 20mm) 4-32 15 Steps (Diameter 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 32mm)Package Included:1 x Stonego Step Drill BitFeatures - Stonego High speed titanium nit-ride coated steel Replaces 29 separate drill bits Two fluted design for fast, smooth cutting. - In order to extend the service life of the drill bit, please inject cold water while working. Stonego recommend drilling rate of 250-250 RPM. - 1mm thickness can be operated by hand drill, 2~3mm please use bench drill. Stonego drill must continue to cool down when it is working, and it is not easy to burn. - According to the need to process different diameter holes, you can achieve one-time processing of large holes, no need to replace the drill bit and positioning hole.Note 1) Start drilling at low speed. Do not push too much. Let the drill bit to cut by itself. The harder the material it is working with, the lower speed shall be applied. 2) Suitable for use in the hardness below 25 degrees workpiece, such as iron plate, copper plate, aluminum plate, the thickness of the plate of step is 3mm and wood, PVC sheet, insulation boards with a thickness of 5mm(0.2 inch) or less. Can not be used to hard and brittle materials such as stainless steel, glass, tile floors, walls etc.