• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Stabilovolt regulators?

If you do not like the logo and text on the tube then just whipe it off and treat it as any other tube.

If you do not like the origin of the tube or under what condition it was produced then get rid of it.

The choice is yours i guess.

Best regards,
Frank