... "(152mm), 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 ... 5/8"(346mm),14 3/4"(374mm), 15 1/2"(394mm)16"(406mm), 17 1/2"(445mm),18"(457mm), 26"(660mm)Model NO.437 ... matching cutting structure with different tooth shape, tooth density and tooth exposure height. 17 1/2" milled tooth tricone bits for well drilling mine drilling