... bits, Milled steel tooth bits).: "8-1/2","9-1/2","12-1/4","15-1/2","17-1/2 to 26,We have been serving the ... hardfacing on the shirttail increases gauge holding capability and bearing life.3.Bearing Structure of this series tricone rock bit :High ... /8 ,5 1/2, 6 1/27 7/8,8 1/2,8 3/410 5/8,12 1/413 3/4, 17 1/2,22, 24, ... , then 70% paymeny after see the B/L)Other Sizes and Model We can Provide 60mm,65mm,76mm, ...