... the Certificate of ISO9001 in 1999 Tapered Button bits, Retrac Button Bits, Rock tools, Rock drilling tools, ... controlled heat treatmentMore experiences in exporting with leading qualityTapered button bits (28mm, 30mm 32mm, 34mm, 36mm, ... 38mm; Round 32mm, 38mm, 45mm, 51mm)Retrac Button bits with different Thread different diameters. (51mm, 64mm, ... :Spherical, Ballistic retrac and drop center button bits