The 031-6861: The kit includes four pieces: the connector body, a gold-plated brass centre contact, a crimp ferrule, and a PTFE insulator, all assembled in the field onto LMR-240 cable.
Cable Fit and Termination — LMR-240 Specific
This connector is dimensioned for LMR-240 coax — a low-loss cable with a 0.240-inch OD, 50 Ohm impedance, and a solid or stranded centre conductor. The shield termination is crimp (the ferrule compresses onto the braid), while the centre pin is soldered to the conductor. If you're terminating a different cable type, the dielectric diameter and jacket OD won't match the ferrule and insulator bores.
How It Compares to Nearby Peers
The 031-70558-12G is also a BNC plug but at 75 Ohm impedance for Belden 4694P cable — it won't match a 50 Ohm system. The 034-1118-12G is a 75 Ohm HD-BNC plug for Belden 1855A/4855R, with a smaller form factor and 18 GHz ceiling, but incompatible with standard BNC jacks. The 031-6928 is a bulkhead jack (female) for LMR-240, IP67 sealed — same cable group, opposite gender and mounting. None are a drop-in swap; the 031-6861 stays the correct 50 Ohm male plug for LMR-240.