... drill bit sets: 1.clay,quarrying,mining,construction button bit 2.button,thread,tapered bit 3.chisel,cross,button etc Oil drill ... a) high air pressure: Cop, Br, HD, XL, QL, Mission series. (b) low air pressure: CIR and J seriesNote: We can ... cruciform type rock drill bits : Applicable with larger impact energy rock drills, under the condition of cut fractured rock drill and abrasive strong rock strata, ...