Steel Tooth Tricone Bits 1)certified by ISO9001&API 2))used for water well, oil field 3)multiple gauge ... 3 7/8" to 26" , normal sizes consist of 5 7/8", 6", 6 1/2", 7 1/2", 8 1/2", 9 1/2", 9 5/8", 9 7/8", 12 1/4 ... ",13 5/8", 14 3/4", 15 1/2 ... ", 16", 17 1/2 ...