Why only four stars?
The instructions for assembly is unusable, the tool provided is not sufficient, it was missing a washer and inserting the roll was so stiff that it was to accomplish only with rubber mallet and intermediate piece of wood.
So if you have no experience with such furniture and no complementary tool at home, should stay away from this chair. It was really stressful.
Now I am satisfied owner of a very good office chair at a moderate price.