Oil Rig Drill Bit Size range from 3 7/8"to 26" Certification ISO and API Oil Rig Drill Bit1. Cutting Structure of this ... on the tooth surfaces for steel tooth bit.2. Gauge Structure of this series tricone rock bit :Multiple gauge protection with gauge trimmers ... .mm6152.4 4.7,517, 537, 617, 637 6 1/2 165.1437,517,537,617,6377 1/2190.5517, 5378 ... , 537,617,63717 1/2444.5517,535,537 Oil Rig Drill Bit