... High-precision metal seal. 3. Locking roller ball, to adapt to high-speed. 4. The use of high strength high ... the role of broken rock. 6. Cone bit to adapt to the soft, medium and hard of various strata. ... -5/8, 12-1/4 Various sizes also can be made to order. Types: IADC Code, 412, 432, 532, 612, ... 712, 732, 832 etc.Non standard also can be made as your requirements.If you have any questions,please do ...