... insert bit ,TCI bit,button bit 1,Sizes range from 3 7/8" to 26" . 2,Reliable bearing and lubrication system 1.Cutting ... applications.5. 5.Current Main Availability Diameter/InchIADC CODE3 1/2 211, 121, 241, 537….3 7/8 ... , 537, 517….6 211, 121, 241, 537…. 12 1/2 211, 121, 241, 537….14 3/4 131, ... 1/2 131, 211, 537, 517….18 1/2 211, 121, 241, 537….………..………………………………26 131, 211, 537, 517…. TCI rock bit