... treatment: Black Nitride3. point angle:118°or 135°4.For drilling in steel,cast steel,malleable iron,sintered metal,non-ferrous metal ... resistant8.Certificate:ISO9001:2008 Quality Control:In the quality control process,we pay attention to in every details to products checks,pursuit ... quality and service.Fangda holding Co.,Ltd. is biggest company in our town,which is Chinese drill bits base. We are ...