high quality tungsten carbideDrill bits good copper brazing material Used in drilling on marble, concrete and granite ect. Diameter: 6-40mmLength: 110mm, 160mm, 210mm, 260mm, 310mm, 350mm, 400mm, 460mm, 500mm, 600mm, 700mm,800mm, 900mm, 1000mm.material: 40 cr steel, YG8C carbidesurface treatment: sandblastWe can supply all kinds of SDSdrill bits according to customer's requirements.