Embossed steel. Embossed inside. Mineral water. Production period: 1988.
Inscription on cap: Пятигорск ПЗ Машук - 19 1-8-1988
This differs from RU600401-1001 by having a different font.
There are caps with lacking a dot between П and З, as well as without a dot.
© Image by Alexandr Efimov