Obviously a variant of the Produx. The Tip is the only physical variant that I have seen with the 'Subtraction' and 'Addition' spelled out instead of using the '-' and '+' symbols. The ad at Produx, however, does show a Produx with the words spelled out.
Yes, product of Otto Meuter (Product name = Produx) F. Diestelkamp 17:08, 16. Nov 2011 (CET)