This lamp is from 1952 (AR 17) and is fitted with the plain parchment shade, so it is option /8 (the shade is a reproduction). A curious point is that the glass is marked Optimus. As far as I know, Optimus never made a lamp that used a glass of this size. One theory for this could be as follows. After Optimus took over the Primus production, I assume they also had to supply spares for older models. As the order came from Optimus, Schott must have put their logo on the glass instead of Primus.