... Pressure RC Drilling bit Bit for down-the-hole drilling, air reverse circulation drilling in mining exploration, civil engineering, ... circulation drilling.Bit Front designs:Complete compatible to be used with DHD hammer DHD330, DHD340, DHD350, DHD360, DHD380, SD18, N180 etcConvex ... , 279mm, 305mm, 330mm, 356mm, 381mm, 445mm, 555mm, etc. Down The Hole Drilling Bit