... ) high air pressure: Cop, Br, HD, XL, QL, Mission series. (b) low air pressure: CIR and J seriesNote: We can design ... bit, long skirt l For H22 drill rodButton bit l General purpose bit Retract button bit, long skirt l Design to provide ... and completion of bit in adverse hole conditionsFlat face l General purpose bit l Suitable for medium to hard rock Drop face ...