drill bits,drill segments,hss drill bits are used for cutting all kinds of stone.diamond drills.over 20years ... ,Φ36,Φ46,Φ59,Φ60,Φ66,Φ75,Φ76,Φ91,Φ94,Φ1102,single tube drill:Φ36,Φ46,Φ59,Φ75,Φ91,Φ94,Φ110,Φ130 ... ash zone;sandstone;shale;2,middle-hard stone:Fine single limestone;Reinforced concrete;dolostone;Hard sandstone;other middle-hard stones3, hard-stonebasalt ...