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8 1/2 refers to the size 8 1/2"; 5 refers to tungsten carbide inserts bit; 3 refers to Low compressive strength of soft to medium formation; 7 refers to journal bearing roller bit.
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8 1/2 refers to the size 8 1/2"; 5 refers to tungsten carbide inserts bit; 3 refers to Low compressive strength of soft to medium formation; 7 refers to journal bearing roller bit.
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