Use the .255 Hex for crimping the rear ferrule to the following coax types:
RG-8X                  Belden 9258
RG-59                  Belden 8241
RG-6                    Belden 7916A
LMR-240
LMR-300
RG-62                  RG-223
Use the .213 Hex for crimping the rear ferrule to the following coax types:
RG-58                   Belden 9201
RG-58A/U           Belden 8219
LMR-195             Belden 8259
LMR-200
RG-142
RG-400                Belden 7807