... using round premium 13.4mm inserts. long life and high penetration PDC bit----PDC inserts are set in a cast ... matrix head using round premium 13.4mm inserts. PDC bit ... coal, oil shale, tarsands, and shallow oil and gas.PDC bit : 56, 60, 76, 96, 113, 123, ... & inner tube wrench, foot clamp,etc. PDC bit for core and nocoring,carbide, stronger, long life