There are several models of the Industar 61. A few things to thing about include:
Color of the lens - Comes in various silver, black, black and silver colors. Some copies have a smoother ring compared to the versions with cut outs.
Aperture ring - Some lenses have a smooth, click less aperture while others are clicked.
Focal Length - Depending on the year and run, the Industar 61 has a focal length of 50mm, 52mm or 53mm.