... and low air pressure dth button bit. (a) high air pressure: Cop, Br, HD, XL, QL, Mission series ... . (b) low air pressure: CIR and J seriesNote: We can design and manufacture according to ... the condition of cut fractured rock drill and abrasive strong rock strata, resistance to abrasion ... than chisel bit strong applicability hammer, speed and life and high, cut out of a round shape ...