The 413985-3: This plug is designed for RG-174, RG-188, and RG-316 coaxial cables — the common small-diameter 50-ohm types used in RF modules, antennas, and test leads. The kit format means you don't have to source the contact and ferrule separately for a single repair or prototype run.
SMB vs BNC — Interface Difference
This is an SMB connector, not a BNC. The snap-on coupling is smaller and faster than a BNC's bayonet lock, and the SMB interface is rated to 4 GHz versus a typical BNC's 1-2 GHz limit. The trade-off is lower mating cycle life — 500 cycles here against a BNC's typical 500-1000 — and no 75-ohm variant in this series. If your system calls for BNC, the 413985-3 will not mate.