... 1). High quality and competitive price 2). many years experience in well drilling equipments Available sizes:4 5/8"(118mm), 5 7 ... ), 6 5/8"(168mm),7 1/2"(190mm), 7 7/8"(200mm),8 1/2"(215.9mm), 9 1/2"(241mm),9 5/8 ... "(245mm), 11 5/8"(295mm),12 1/ ... tooth shape, tooth density and tooth exposure height. 17 1/2" milled tooth tricone bits for well drilling mine ...