... ), 6 1/2"(165mm), 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 ... 3/4"(374mm), 15 1/2"(394mm)16"(406mm), 17 1/2"(445mm),18"(457mm), 26"(660mm)Model NO.437,447,517,527, ... shape, tooth density and tooth exposure height. 17 1/2" milled tooth tricone bits for well drilling mine drilling