... 149mm), 6"(152mm), 6 1/2"(165mm), 6 5/8"(168mm),7 1/2"(190mm), 7 7/8"(200mm), ... ),14 3/4"(374mm), 15 1/2"(394mm)16"(406mm), 17 1/2"(445mm),18"(457mm), 26"(660mm)Model ... new formulas and new techniques for insert bit. 2>Gauge Structure Multiple gauge protection with gauge trimmers on ... different tooth shape, tooth density and tooth exposure height. 17 1/2" milled tooth tricone bits for well drilling mine ...