1.For Gravel,the loose stratum,the complex stratum 2.certified ISO,API 3.wide size code 4.best price 5.delivery on time We are a professional company in supplying tricone bits,steel teeth bits,single cone bits,and PDC bits. Bits sizes range from 3 7/8” to 26”.and cover almost all IADC codes.It can be used in various of different fields,mining,hydrology,subterranean heatpilling,water well drilling ...