You are bidding for a cosmetically and functionally excellent FLEKTOGON Auto/Manual Multi Coated 2.4/50mm Lens with an M42 screw mount, produced by Carl Zeiss Jena.
 Serial # 44586.
Diaphram is nice and snappy and is dry, no oil residue, can be used in both auto or manual.
Bodywork is also great.
Lens is clear of fungus, Haze or cleaning marks, a really good example.
Included are front and rear caps and leatherette pouch.

This lens has M42 screw mount, so it will fit on all M42 35mm SLR FILM CAMERAS. 

Also fit on many other SLR, DSLR or MILC cameras with using a correct adapter. 
(Canon FD, EOS, Nikon F, Sony Alpha, Minolta MD, AF, Pentax K, Olympus OM, E 4/3, micro 4/3, Sony NEX, etc.) 
Many adapters are available on ebay. 

Technical data: 

Vendor name: Carl Zeiss Jena
Type: Flektogon
Focal min: 35mm, focal max: 35mm
Focus min: 0,19m (!!!), focus max: infinity
Aperture max: 2.4, aperture min: 22
Barrel length: 0.61m
Elements in group: 6 in 6
Diaphragm action: auto/manual
Weight: 248g
Filter size: 49mm
Push on diameter: 51mm
Angular field: 62