Santini pens with Flexy nibs must have ebonite feeds. Some of the pens I'm looking at are made of acrylic resin and others are ebonite. The former cost 259 euros and the latter cost 359 euros.

What are the advantages and disadvantages of each? What do you get for 100 euros more when you get an ebonite pen?

Examples of Ebonites are Libra Blackberry, Mora, Sand, Acqua, Cumberland, Ginger, Ethiopia and Lava. Examples of Acrylic Resins are Libra Black, Nut, Lord, Etna, Grape, Laurel, Diamod Blue, Lavender, Royal Blue, and Red.