Tricone bit Cuttingstructure: very long widely spaced , chisel-shaped inserts and considerable coneaxis offset against center line of bit ensure very high penetration rate . Tosecure the bit from diameter loss, the gage protection inserts have got shorterlength and greater angle of the top. Formations: long intervals of very softpoorly compacted shale, sandstone, clays, salts and soft mestones. Size andIADC available: 2 7/8 to 26 IADC 114 117 216 217 317 321 417437 517 537 617 637 and so on.