Independent ballast for 250W Mercury Vapor lamps, classics for upgrading of all kinds of "hat luminaires" and part of SZPR-250 luminaire. These are ideal for dry conditions, but they can also work outdoors. The problem is that the cover screws rust, the seals crumble and water flows freely inside. We call all chokes of this type simply "gatchin".
The exhibit is in a "new" condition, never used.