Strange. I never saw an european style electronic ballast for krypton T8 lamps that can also run the former argon T12 lamps the krypton T8 lamps are intended to replace. I think this is because this is an old ballast. All 90s and later electronic ballasts for krypton T8 lamps can run only krypton T8 lamps and not the former argon T12 lamps.

It is probably made before 1994, because it has no CE mark, which was introduced here in 1994.

Are you sure new electronic ballast can't run T12 lamps, or did they just stopped printing 65/40/20 W on them because the lamps are so uncommon today?

I think modern electronic ballasts for krypton T8 lamps can't be run the former argon T12 lamps. Otherwise they would print. But maybe they can run argon T12 lamps, and the companies aren't write this to deter lighting companies to continue to make argon T12 lamps to these electronic ballasts and at all.

There is no issue with running older T12 lamps on any newer ballast designed for T8's at all, not only electronic. T12 lamps are simply not printed, as they are intended for use only as replacement lamps in old installations (with older ballasts,...), that have problems running T8 lamps and the intention is to phase T12's out. Due to their oddity they bear higher expenses mainly in logistic, but due to their obsolescence their sales cost can not rise, so they are more a burden for manufactures and are carried only as a marketing signal "you might rely on us for replacement lamp supply for whole installation life, even if they become obsolete, so don't hesitate to specify our products". And because they do not want to manufacture them really forever, they discourage their use for any new application.

@ Medved: so your saying that they're made as replacement ballasts?
That's what I'm thining

Maybe...
But i think it was more due to the time, when this ballast was introduced. Then T12 were still quite common, so this ballast was specified them as well...