This Russian made 2x yellow filter for b/w film is designated
for the Russian collapsible lenses - Industar-22 and Industar-50.
The filter is a 36mm slip-on type. The filter is
marked ZhS-17. It was made according to the same standard by several manufacturers
- KMZ, LZOS and others.
Please ask me if you are not sure about your lens.