This black Souvern fountain pen is made with a semi-translucent, high-grade resin casing and features an inbuilt differential piston filling mechanism. Pelikan was the first company in the world to introduce the differential piston mechanism in 1929. 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. The design has since evolved but the basic mechanism remains the same even today and is used in many pens. This models palladium-plated trims and green ink window give the instrument a unique and splendid style. The pens 18k gold nib is completely rhodanised to obtain a silver sheen. The high-quality nib is available in Extra-Fine, Fine, Medium and Broad.