A Pelikan Souveran nib unit to fit M200/M400/M600. 14ct two-tone gold with a Hard Extra FIne point. I have two of these for sale at £45 each. They simply screw into the barrel unit. The difference between a standard and a hard extra fine is that there is no flex with these, so they are perfect for fine figure work. Pelikan no longer make these hard nibs.