8 1/2" Tricone Drill Bits 1-Rubber mealing 2-API or ISO 9001: ... the principle of "faith-based, quality of survival and mutual benefit, provides the highest quality products and attentive service for ... the near future Model6-171/2( inch) TypeTricone bits, Steel tooth bits, PDC bits Applicable water well, oil field, construction, geothermal, ... 637G17 1/2444.5517G, 537G, 617G, 627G, 637G cone mining bits