... has over ten years history of manufacturing the high-speed steel twist drill. It is specialized in producing 4241, ... 6542, M35, M42 high-speed steel rolling drill and all rubbing drill.We are a specialized manufacturer of HSS ... twist drills,taper shank drill,SDS drill bits,center drills,step drills,masonry drill,,wood working drill,flat wood bit, ... free to contact with me. sds electric hammer drill set