This is a Conklin Nozac Word Gauge 5M Demonstrator piston filler in the rounded shape c1934-1936. The Word Gauge Nozac was introduced, based on Conklin advertising, in 1934. Each of the markings indicated a thousand words, so a 5M pen would be 5,000 words. The Word Gauge pens came in both rounded and faceted versions. Unknown if the Demonstrators were made faceted. This 5 1/4 inch long pen has barrel stampings "The Conklin Pen Co., Toledo, Ohio, U. S. A., NOZAC, Reg. U. S. Pat. Off." on one side of the barrel and "U. S. Pats., 1902809-10-11" on the other side. The pen has the April 28, 1918 patented Conklin clip. Conklin introduced the Cushon Point 14 karat gold nib in 1936, so either the nib on this pen is a replacement, or the pen was later production.