It is the female, panel-mount half of a standard BNC bayonet-coupled pair, terminated with a right-angle solder tail that routes the centre conductor parallel to the PCB.
RF and mechanical ratings
The 4 GHz max frequency is the upper end of the usable bandwidth. The bulkhead mount with a front-side nut secures the connector to a panel cutout, and the board guide on the right-angle solder tail helps align the pins during hand assembly or wave solder.
No official cross-reference or direct equivalent is on record, so match the BOM line to this exact order code.