The pPen Devil was another of those good ideas that never caught on. It one of the first long 7mm mandrels for turning both pen barrels of the Slim-Line pen at the same time. If I remember right, the center bushing was machined as a part of the shaft. It was advertised as being more accurate than the others at that time because it was a floating rod that was supported by a drive attachment that you had to turn yourself.
I don't think it ever sold very well because it was more expensive than the other mandrels, worked for only one pen (SlimLine), was more difficult to use than the other mandrels, and was never marketed by the pen dealers who had their own mandrels to sell. Oneway dropped it from their catalog several years ago.
