The Mir-1 (МИР-1) is a wide-angle lens for SLR. It was made for M42 and M39 mount cameras. There also exists a version for the Kiev-10, which uses a special bayonet. Its design is derived from the Flektogon.
The first lenses were produced by KMZ around 1955 (Princelle K1620). They surface infrequently on ebay and often command higher prices then the later versions made by ZOMZ (Загорский оптико-механический завод) in Zagorsk. The early lenses also bear the П-coating label on the lens front plate. Every MIR-1 lens produced after 1958 bears a "GRAND PRIX Brussels 1958" inscription, referring to the prize the lens won at the 1958 world expo in Brussels.
Princelle lists my copy as Zg50.
Aperture range: f/2.8-f/16
Minimum distance focussing: 0.7m
Aperture blades: 10
I have seen this lens in silver and in black finish; with Latin and cyrillic script; with factory labels of KMZ, ZOMZ and Valdaï. My copy is Zg50, silver version with Latin script, produced by ZOMZ in 1969 (cf. serial number). Quality wise, this lens is not bad, but I don't really like the combination with the NEX-5. This is just a subjective personal preference though.
You can take a look at the Mir-1's dedicated gallery
The ARG-file I use with exiftool: mir1-37f28.txt
-EXIF:LensModel=Mir-1 37mm f/2.8 (M42)
This works for LR4 and NEX-5 RAW-files.