This Faithfull Professional Holesaw 9 Piece Kit contains six of the most frequently used holesaw sizes. These high speed steel bi-metal saws have specially hardened variable pitch teeth for fast smooth cutting. Bi-metal saws offer increased safety as they will not shatter under load.These holesaws are used to cut perfect holes in a wide variety of materials including wood, chipboard, plywood, non laminated plastics, plasterboard and non ferrous metals. Suitable for use in most variable speed power drills. Supplied in a sturdy zip-up case. Contains: 6 x Holesaws: 19, 22, 29, 38, 44, 57mm.2 x Arbors: 7/16in Hex, 3/8in Hex.1 x Arbor Adaptor.Additional Information:• Material: Bi-Metal• Pitch: Variable