Industar-22 red P 3.5/50 USSR lens for SLR Zenit KMZ M39 mount

Industar-22 red P
silver lens for SLR, #5410585
50 mm, f/3.5, M39*1/45.2 mount , 
Krasnogorsky Mechanical plant (KMZ), Krasnogorsk, USSR

Very good condition. Lens is clear and clean, without any fungus or scratches. Inside there are microspecks of microdust. Aperture and focus rings rotate tightly. Both rings have a backlash. Body has signs of age and use.

Camera "Zenit" is not included and shown as an example of mount.
Please, note that it's a lens for SLR, not for rangefinder.

This is a standard lens with antireflection coating for Soviet SLR cameras "Zenit". Firstly was named "OI-22", then got the actual name "Industar-22". Lens was designed in 1945, started to produce in 1948. In the end of 1950-s "Industar-50" was introduced instead of "Industar-22".

Lens was based on Leitz Elmar 3.5/50 from Leica II, but the aperture blades in Elmar is between first and second lens, in "Industar-22" it moved between second and third lens. In the end of 1950-s "Industar-50" was introduced instead of "Industar-22".
Also there was "Industar-22U" and "Industar-22U1" for enlargers and version for rangefinders "Zorki".
This lens was made at Krasnogorsky mechaical plant named after Zverev (KMZ), also it was at KOMZ (Kazan). 
 
Lens s/number - 5410585
Number of lenses - 4 in three groups.
Angle of view - 46o
Number of aperture blades - 8
Limit of aperturing - 1:3.5 (max), 1:16 (min)
Resolving power - (centre/edge) 32/22 lines/mm
Minimal distance of focusing - 1.25 m
Type of thread - M39x1/45.2
Type of thread for the nozzles -  33 mm 
Dimensions (mm): 56*48*30
Focal distance - 51,39 mm.
Mass - 74 g
One-layered antireflection coating