The "D" revision is the anomaly. Versions A, B, and C are traceable. They were standard AES-256 tokens. But the ? It contains a custom FPGA fabric that no one has been able to fully emulate yet.
This is the creepy part. When you plug a standard engineering key into a host machine, it leaves logs (Event Viewer, syslog, etc.). The KPG-111D reportedly from RAM before the OS writes the log. Security researchers have only found evidence of the key’s use via thermal imaging of the CPU die itself.
Check your old parts bin. If you find one, don't sell it. Guard it. And whatever you do, don't plug it into the company mainframe on a Friday afternoon.