Galaxy Audio CN-BNCPM Front-Mount BNC Connector

The CN-BNCPM is the bulkhead half of a front-mounted antenna. It fits through a rack ear so the antenna lives on the front of the rack, out where it can see the transmitters, rather than buried behind a door.

It is the connector only. An EXTBNC extension cable is needed to run back to the receiver, and Galaxy also sells the two together as a cable and connector combo kit.