Combined Center Drill Countersink Ti-Coated 60 Degree Angle Bit Set 6pcs 1.0-5mm. Type: Center Drill Bit. Material: High Speed Steel. SKU1: Material: HSS4341 (1.0, 1.5, 2.0, 2.5, 3.0, 5.0) 6 sticks, suitable for processing materials with low hardness. SKU2: Material: HSS6542 (1.0, 1.5, 2.0, 2.5, 3.0, 5.0) 6 packs, suitable for processing aluminum, copper, and iron materials. SKU3: Material: HSS4341 titanium plated (1.0, 1.5, 2.0, 2.5, 3.5, 5.0) 6 packs, suitable for processing materials with low hardness. SKU4: Material: HSSM35 (1.0, 1.5, 2.0, 2.5, 3.0, 5.0) 6 sticks, suitable for processing steel parts, stainless steel and other metal materials.