Tungsten carbide insert bit ,TCI bit,button bit Sizes range from 3 7/8" to 26" . ... and lubrication system Detailed Product Description Tungsten carbide insert bit ,TCI bit,button bit Sizes range from 3 7/8" to 26" ... for mining applications. 5.Current Main Availability Size Bit TypeIn.mm8 1/2215.9622,632,7329 5/8244 ... 4311.1622.632 API 12 1/4'' tricone rock bit for oil drilling and water drilling