... performance: High speed,Smooth cut. Electro-plated diamond core drill bit (hole saw) :-Fast, clean and efficient ... ). Diameter: from Ø3mm to Ø127mm(2). Shank/Top: Round, Trigonal, Hex (3). Diamond grit: D427, D252, D181 ... bag; Blister; or as your requirement (6). Used to drill marble, ceramics, porcelain, tile, glass, fiberglass, quartz, bricks ... or without center pin. Diamond core drill: round shank