... strength and high drillability,such as soft shale,clay and salt bed,etcHardfaced gage and all tooth ... strength and high drillability,such as soft shale,clay and salt bed,etcHardfaced gage and all tooth surfaces ... low compressive strength and high drillability,such as shale,clay,sandstone and soft limestone,etc.Large radius offset ... ,130.2MM,142.9MM,149.2MM,152.4MM,155.6MM,158.7MM,171.4MM,190.5MM,193. ...