Jupiter-12, black lens for microfilm projector "Mikrofot"
35 mm, f/2.8, special mount, s/n 8417104 
Lytkarinsky Plant of Optical Glass (LZOS), USSR, 1984

Very good condition. Lens is clear and clean, does not have any fungus. Rear glass has scratch at the edge. Inside there can be microspecks of microdust. Body has small signs of age and use.

This is the variant for viewing microfilms on 35-mm film from the "Mikrofot" projector. The optical scheme, number of lenses is the same, but this lens does not have a mount and was inserted in the projector. It does not have an aperture or focusing mechanism.
"Mikrofot" was equipped with two lenses: "Jupiter-12: for half-frame microfilms (24*18mm) and "Jupiter-8" for full-frame (24*36mm). 
It can be used as a donor of lenses for standard "Jupiter-12" with M39, but the lens must be adjusted then. If the year of production of donor and the lens is close, very often adjustment is not necessary.
 

Lens s/number - 8417104
Number of lenses - 6 in four groups.
Angle of view - 62o50'
Number of aperture blades - none
Limit of aperturing - 1:2.8
Resolving power - (centre/edge) 34/12 lines/mm
Dimensions (mm): 51*51*45
Focal distance - 35,75 mm.
Mass - 106 g