The 1-1634816-0: It's a replacement or spare nut for BNC and TNC connectors, finished in nickel over a brass body.
Obsolete — Sourcing Reality
There is no listed direct replacement from TE.
The nut fits standard BNC and TNC connector interfaces — it threads onto the connector body to lock the mating pair. The nickel-plated brass construction provides corrosion resistance and RF shielding continuity.
