... 116,517,537,617 4.oil drilling, water well drilling 5.ISO,SGS approve Rock Bit1.Type:TCI -tungsten carbide insert ... 5MM.we can make the diamater size of the rock bits as cutomers request.the diamater size show in ... execlPls see other details:Available IADC code of rock bits Milled tooth:116,117,126,127,136,137 ... .Contact:Rita FengPhone:86-18730702717 water well Rock Bit for hard formation size 8 1/2''