Converter for C499 fountain pen. Use for product: Cartridge fountain pen. Tank mechanism design: Twist mechanism. The converter enables fountain pens to be filled from the ink bottle. The converter is installed in the fountain pen like a cartridge. The fountain pen is then dipped into an ink bottle until the nib and part of the grip are immersed in the ink. The rotary knob of the converter is then turned until the ink is absorbed.