... shirttail increases gauge holding capability.3. Bearing StructureAir cooling roller bearing package. Balls lock the cone which reduces the ... mining applications.5. 5.Current Main AvailabilityDiameter/InchIADC CODE3 1/2 211, 121, 241, 537….3 7/8 131, ... 537….4 3/4 131, 211, 537, 517….5 1/2 131, 211, 537, 517….6 211, 121, 241, ... 537…. 12 1/2 211, 121, 241, 537….14 3/4 131, 211, ...