... 2.button,thread,tapered bit 3.chisel,cross,button etc Oil drill bit sets:(single,cross,button Type and high pressure ... suitable for soft rock l 10,000-20,000 PSI (70-140 Mpa)l Non-abrasive ground Bit face designs Face ... suitable drill bits. chisel,cross,button rock drill bit and oil drill bit sets ,high pressure drill bit and tapered thread ...