The collapsible Industar-50 lenses were made by 3 factories: KMZ (Krasnogorsk), KOMZ (Kazan) and LZOS (Lytkarino). The KOMZ version(s) is somewhat uncommon, but the KMZ and LZOS lenses are not difficult to find.

This lens is produced by LZOS in 1960.  Princelle lists it as Lz10.

Aperture range: f/3.5-f/16
Minimum focussing distance: 1m
Aperture blades: 8

It was commonly mounted on the Zorki-5 and Zorki-6. I have already seen a few varieties of this lens, e.g. serial number variations (N° vs N) and engraving styles (e.g. 5cm. vs. 50/3,5). Perhaps that, on a rainy day in winter, I will try to catalogue all known LZOS varieties :-)

This copy bears the П-mark, indicating that it was coated. It has 8 aperture blades, which stands in contrast to the 10 aperture blades of the KOMZ Industar-50. I have a KMZ Industar-50 as well (not yet published on my blog); it also has 8 aperture blades.

The ARG-file I use with exiftool for this lens: industar50lzos_6002087.txt

-n
-ex
-XMP:SerialNumber=6002087 Π (LZOS)
-XMP:Lens=Industar-50 5cm f/3.5 Π (M39)
-EXIF:MaxApertureValue=3.5
-EXIF:FocalLength=50
-EXIF:FocalLengthIn35mmFormat=50
-EXIF:FNumber=3.5

This works for LR4 and NEX-5 RAW-files.