air /petrol /electric rock drill from china type:YT24,YT28,YN30,YN30A,YN30E,YN27,YN27C,YN27T certificate: ... ISO9001,CE super air /petrol /electric rock drill from chinaFeatures 1. The Internal Combustion Rock Drill is a hand ... to work on high mountains, and places with no power supply and air compressing equipment, and especially suits the temporary projects ...