... 2" Steel Tricone Drill Bits 1-API or ISO 9001:2008 2-Delivery Date: In 7 days 3-Delivery term: By sea/air ... formations(114-117)These bits are designed to drill the softest formations such as soft shales,red ... ,134,136,137)These bits are designed to drill formations such as shales, medium soft limestone, ... 213,214,215,217)These bits are designed to drill formations such as hard sandstone, dolomite, and ...