This product is packaged in a MIL SERIES CONNECTOR box.BOARD AND PANEL indicates that the device is mounted.Furthermore, there are other features such as STANDARD: MIL-DTL-38999, EMI SHIELDED, to name a few.
D38999/21HG11DN Features
D38999/21HG11DN Applications
There are a lot of TE Connectivity Deutsch Connectors D38999/21HG11DN Circular Connectors applications.