You'll get MIL SERIES CONNECTOR packages.BOARD AND PANEL is the mounting type of the device.To name a few, there is also STANDARD: MIL-DTL-38999, EMI SHIELDED, POLARIZED.
D38999/21HE99CD Features
D38999/21HE99CD Applications
There are a lot of TE Connectivity Deutsch Connectors D38999/21HE99CD Circular Connectors applications.