... circulation drilling. down the hole High Pressure RC Drilling bit Bit for down-the-hole drilling, air reverse circulation drilling ... well drilling, geothermal well drilling, reverse circulation drilling.Bit Front designs:Complete compatible to be used with DHD hammer ... DHD360, DHD380, SD18, N180 etcConvex Front, Flat Front, Concave Front, Concave DGR Front etc.Bit Dia. 85mm, 90mm, 95mm, 102mm, 105mm ...