... 8"(346mm),14 3/4"(374mm), 15 1/2"(394mm)16"(406mm), 17 1/2"(445mm),18"(457mm), 26"(660mm)Model NO.437 ... 537,547,617,637,737IADC CODE116,117,126,127,136,137,216,217,316,317,346,347RPM(r/min)140~60WOB ... is improved with new formulas and new techniques for insert bit. 2>Gauge Structure Multiple gauge protection with gauge trimmers on the ... you best quality with the most competitive price! tricone rock bit