... 4.Good hole quality. DTH Hammer Button Bits For Rock Drilling Description:DTH Drill Bits are produced from premium quality nickel-alloy steel for ... DHD3.5,DHD3.5HD,DHD 340A , DHD350R, DHD 360, DHD380 QL40, QL50 , QL60, QL80.Product features: DTH hammer bits are designed for maximum ... ,bit after bit.With the original manufacture such as DHD models of INGERSOLL-RAM,models of MISSION.Overburden drilling ...