... 2.Fast drilling rate 3..size rang from3"1/2-26" 4.Certification: API & ISO9001 5.delivery on time ... 371mm), 15"(381mm), 17 1/2"(445mm), 24"(609mm), 26"(660mm)IADC 147,437,447,517,527,537,547 (HJ ... 547 516 536 535available sizes:From 2 7/8 to 26”larger sizes for hole opener bit ,reamer bitadvantagemost favorable ... adequate sealing for bearing durability. 3 1/2"-26" Kingdream water well reamer bit