DKL 1.5/2.5cm lens in C-mount

Rear thread is 25.4mm, so it is C-nout most probably.

Aperture and focus rings work fine.

Aperture values are f/1.5-11

Distance scale is quite strange - marked in centimeters from 14 to 80.

Collar with index mark is loose, and mount itselt is loose too. So, the lens requires minor fix. That is why price is so low.