The 500 mating cycles are typical for a bayonet-lock BNC; the coupling wears with repeated connects, but 500 is a solid service life for field-swappable cables.
The body is zinc with a nickel finish — corrosion-resistant and durable for panel-mount service. The centre contact is phosphor bronze with gold plating, which keeps contact resistance low and survives repeated mates. Termination is solder cup on the centre pin and solder on the shield braid — a clean, reliable joint for a permanent cable assembly.