... bits, down the hole bits, Drop centre retrac button bitsOwn a factory for raw material. Material quality stableComputer ... controlled heat treatmentMore experiences in exporting with leading qualityTapered button bits (28mm, 30mm 32mm, 34mm, 36mm, 40mm, ... R28, R32, R38, T38, T45, T51 etc.) Retrac Button bits with different Thread different diameters. Tooth type Spherical, BallisticDETAILED ...