PLK995308 Piston filler with a 24 carat gold plating and a high-quality resin casing and a viewing window to monitor the ink level. The nibs of the Souveran piston fillers M1000 and M800 are made of 18 carat/750 gold the nibs of the models M600 and M400 are 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 models M1000 and M800.