... etc Oil drill bit sets:(single,cross,button Type and high pressure type)We have many kinds of drill bits for ... Buttons): spherical, ballistic and conical.5) DTH bit, in contains high air pressure and low air pressure dth button bit. (a) high air pressure: Cop, Br, ... suitable drill bits. chisel,cross,button rock drill bit and oil drill bit sets ,high pressure drill bit and tapered thread drill bit