... 517,547,617,637Applicable forPetroleum & gas, water well and mining Bearingmetal bearing(HJ), rubber bearing(HA)Advantagehigh ... quality with reasonable price because of used productFormationsoft and medium formation, hard formationButton bitsmall tooth, big tooth, ... Asia, south AmericaReputation First, Client's Requirement First. How to judge the quality of the used drill bits:1>the ...