... for bearing durability. More size Model114, 126, 117, 127, 437, 517, 537, 617, 637,737,827 TypeTri ... tricone bit),both of which are used for mining pilling, water well drilling or oil well drilling2 ... 2”),508(20”),558(22”),609.6(24”)660.4(26”) Steel tooth(IADC)111, 121,131117,124,126,127 ... Name:kingdreamModel Number:HAType:Center Drill BitGuarantee period:2~4 yearsUse:Well Drilling Rotary speed:300~80r/ ...