A true classic pen by Pelikan Souveran M400 Series In the year 1929 Pelikan was the first company in the world to introduce the differentiated piston mechanism. This technique causes the spindle inside the fountain pen to turn quicker than the end piece of the barrel, with the help of two different threads. To this date, this fountain pen exists in many different variations, and though it has been developed in design and technical details over time, the basic mechanism remains the same. The first Souver n models with a black and blue striped sleeve were added to the product range in 1995. The production of the sleeve is an elaborate task, as the cotton material - its formula was developed specially for Pelikan - must go through many manufacturing steps in order to create this striped piece of material. It is bent, smoothed and its contours are diamond-cut. Next, the characteristic double clips at the back of the barrel and on the cap are integrated into the material. This is done with the highest precision in order to obtain a virtually seamless transition between the materials. The writing instrument is then polished to a high sheen before the slightly springy clip with its famous, stylized Pelikan is mounted. Piston filler including a 24 carat gold plating and an elaborately striped body made of celluloid acetate. The nib of the Souver n piston filler M400 is made of 14 carat/585 gold. All nibs are refined with a rhodium decor and their writing qualities were tested by hand. The fountain pens are equipped with a differential piston-filling mechanism, of which is elaborated with high-value brazen components on the model M800.