... Efficient drilling performance: High speed,Smooth cut. Electro-plated diamond core drill bit (hole saw) :-Fast, clean and efficient ... shank fits all drill chucks-Top of the line core bits for various types of stone(1). Diameter: ... from Ø3mm to Ø127mm(2). Shank/Top: Round, Trigonal, Hex (3). Diamond grit: D427, D252, D181 ... use with or without center pin. Diamond core drill: round shank