How do you recognise a first edition (1965/1967) of the universal Joe Colombo chair compared to later productions?

Universale Chair, model 860 e 86 is the very first production (1965/1976) of the iconic Kartell chair by Joe Colombo.

This first production from 1967 has some differences compared to the later seventies models 4860, 4867, 4868, 4869.

1. They have fins on the side. You will no longer find these fins on seventies models.

2. They have a different stamp on the back, who mention Joe Colombo's professor title.
Joe Colombo was still in the early stages of his professor projects.

3. They are made of hard ABS. These are much solid than the later productions made of soft plastic (polypropylene). The chair seat doesn't fold as it does in later models.

This model is worth a lot more than the seventies models that are often offered for sale.

This 860 e 86 model is exhibited worldwide in prestigious museums such as the Moma in New York, the Kartell museo in Milan, Center Pompidou in Paris and the Design Museum Brussels.