1This machine is made of high quality material, anti-corrosion and durable. 2Ultra-precision drill chuck: special alloy steel production, clamping range 1.5-10mm. 3Adjustable bit clamping range, can be installed different specifications of the drill. 4High concentricity, precise and wear - resistant, non - slip, easy to use. 5Can be used for accurate holing on such precious stone as pearl, beeswax, wood beads etc.