I bought this lens about 1-2 months ago for my Sigma Digital SLR. I just sold the M42 adapter that allowed me to fit the lens to the Sigma so now the lens must go.
Lens is in very good conditions (considering is about 20 years old!). Glass clean. I don't have the front/end caps though (hence the low price). The lens is marked as "Aus Jena" as Carl Zeiss had some trademark issues back in the 70's (I read the stuff on a Praktica website) but it is identical to the Tessar model.
The first picture was taken using this lens. The other picture is the lens itself.
Any questions let me know. Thanks for looking.