3Pcs Set - 4.00 - 12.00 x 1.0mm, 4.00 - 20.00 x 2.0mm, 6.00 - 30.00 x 2.0mm. Universal tool, mainly designed for machining thin sheets. Also used to drill non-ferrous metals & plastic. Special relief grinding provides chatter-free working. Cylindrical steps provide accurate holse sizes.