... down-the-hole drilling air reverse circulation drilling. High Pressure RC Drilling bit Bit for down-the-hole drilling, air reverse ... circulation drilling.Bit Front designs:Complete compatible to be used with DHD hammerDHD330, DHD340, DHD350, DHD360, DHD380, SD18, N180 etc 85mm ... , Flat Front, Concave Front, Concave DGR Front etc.Bit Dia. RC Drill Hammer and Bit