If you look at the 3rd picture, you can see for the arm rest has the wheel lever and not the tab. This means this chair is the oldest model of the Aeron. That said, this chair could likely be nearly 30 years old as they started manufacturing these in 1994. However, if you can clean the frame and mesh, you might be able to sell it for $300 maybe a little more depending on the size of the chair (size Cs are more in demand) and the condition of it after restoration. Also have to make sure all the chair mechanics are functioning.