Is this the hardware you have? [1]

That's some kind of encryption box. It has a "zeroize" button, to clear the keys in an emergency. It might have something that forces uniform latency to make traffic analysis more difficult. Some cryptosystems are totally synchronous, and send random bits at a constant rate when there's no data.

[1] https://www.artisantg.com/TestMeasurement/89462-1/Cyberchron...