Milled tooth bits 1Soft formations(114-117) These bits are designed to drill the softest formations such as soft shales, red beds, and clays, with high durability and maximum penetration rates. 2Soft to medium formations(121, 124, 126, 134, 136, 137) These bits are designed to drill formations such as shales, medium soft limestone, Medium sandstone and other formations with intermittent hard streaks. 3Medium to hard formations(213, 214, 215, 217) These bits are designed to drill formations such as hard sandstone, dolomite, and broken formations with hard cherty streaks
