Double row of teeth API 8 1/2" kingdream PDC bit 1-certified by API ... rows on the bit face. These cutters consist of a layer of polycrystalline diamond on a tungsten carbide substrate and it ... "(8mm),1/2"(13mm),5/8"(16mm),3/4"(19mm),etc.Suitable Formation&ApplicationVarious of hardness rocks or mud except ... well,water well, mining, explorer well drilling. Double row of teeth API 8 1/2" kingdream PDC bit