It uses the DA-15 shell size — the standard layout for RS-232 serial ports, VGA connectors, and industrial I/O panels.
Board Locks and Grounding — Why They Matter Here
This plug carries board locks, a ground strap, and grounding indents — three features that together anchor the connector to the PCB and manage shield current. The grounding indents on the shell mate with the receptacle's dimples to bleed shield current before it reaches the signal pins, which is useful in electrically noisy environments.