1.Certified by ISO9001&API 2.Strong cutting structure durability 3.Fast drilling rate 4.Rubber seal or metal seal Place ... 3/4, 17 1/2,22, 24,26115 116 117 215 216 217 315 316 317 325 327PDC BIT(3 blades,4 blades,5 blades ... ,6 blades)5 1/2, 6 1/27 7/8 ... ,8 1/2,8 3/410 5/8,12 1/413 3 ...