"Hss Step Drill Bits are made of quality HSS steel and coated with Titanium, to reduce friction and heat.100% brand new and high quality and shipped from Germany.Contains padded, aluminum foil protection - Pack size: 15cm x 10.5cm x 4.2cm (L x W x H).Suitable for all sheet metal work and for deburring metals, NE metals and plastics.Material: HSS4241 Long life high speed steel.Product 5Pcs HSS Stepped Titanium Tapered Drill Bit KitThis is the new HSS Steel titanium core drill bit hole cutter, made of high quality HSS steel, coated with titanium to reduce friction and heat. It is ideal for drilling holes in various materials, including steel, brass, wood, plastic, etc. Material The HSS step drill is made of high-speed steel and coated with titanium to reduce friction and heat and increase service life. The three-sided valve stem prevents the bit from slipping; The blade features a double-edged design for faster, more frequent cutting. Note: Check the concentricity of spindle and collet and collet clamping force. since concentricity can cause the tip to break and make the hole too large. Size Different sizes of drill bits to meet your different needs. Specific size: '3/16' to 1/2' 6 tiers (3/16', 1/4', 5/16', 3/8', 7/16', 1/2)' 1/8"" to 1/2"" 13 steps (1/8", 5/32", 3/16", 7/32", 1/4", 9/32", 5/16", 11/32", 3/8", 13/32", 7/16", 15/32", 1/2) 1/4" to 3/4 "" 9 levels (1/4", 5/16", 3/8", 7/16", 1/2", 9/16", 5/8", 11/16 "", 3/4) '1/4"" to 1-3/8"" 10 levels (1/4", 3/8", 1/2", 5/8", 3/ 4"", 7/8"", 1"", 1-1/8"", 1-1/4"", 1-3/8) (3/16"" to 7/8"" 12 levels (1/4", 5/16", 3/8", 7/16", 1/2", 9/16", 5/8", 11/16", 3 /4", 13/16", 7/8) Wide applications: Sharpness and titanium coating make it easy to cut most steel sheets, aluminum sheets, copper, plastic and wood panels and many other types of sheet metal Automatic center punch Center punch provides automatic high-impact spring strike through cap adjustment; its brass body has a deeply knurled surface for slip-free control; and the tip with the carbide tip makes the center punch 10 times stronger than normal, aluminum protective casing to make the tips not easy to dull "