This CD 522.5 has HC18 A (Cyrillic NS18A) and the number 219 embossed.

This appears to be a product of the Lviv Insulator Company in the Ukraine, their product lineup is here: http://www.energyglass.com.ua/en/?topic=nomenclature

the same page in Ukrainian is here: http://www.energyglass.com.ua/ua/?topic=nomenclature

You may have to "click and drag" the entire URL if it doesn't appear properly here.

[IFONA CD 522.5]