... down-the-hole drilling air reverse circulation drilling. High Pressure RC Drilling bit Bit for down-the-hole drilling, air reverse ... DHD hammerDHD330, DHD340, DHD350, DHD360, DHD380, SD18, N180 etc 85mm, 90mm, 95mm, 102mm, 105mm, 115mm, 133mm, 140mm, 152mm, 165mm,178mm, 190mm ... , Flat Front, Concave Front, Concave DGR Front etc.Bit Dia. RC Drill Hammer and Bit