... bearingHJ(metal sealed journal bearing)HA(rubber sealed journal bearing)Aircooled bearing typeFormation or layerSoft, medium soft, hard, medium hard, ... 7 daysapplicationPetroleum and gas, water well, mining and tectonic industries, oil field, construction, geothermal, directional boring and underground foundation work, water ... angles, diamond thickness, chamfers, and sizes. 9 1/2 PDC oil drill bit