These are used on the KI-214 for the glideslope antenna input connection. This small coax connector is very difficult to find. I sell these with or without the KI-214 main connector. It also fits the KI-211C G/S indicator antenna input.
The kit includes parts to adapt the connector to either RG58/A size coax, or RG188 (which is the smaller, thinner cable).
If you don't see the main KI214 connector in the store, let me know, and I can help you find it on this site.