The controller adjusts the 14 kt gold nib from flexible to firm and also changes the width of the stroke. If the controller is twisted in the direction of the "H" (Hard) written on the nib section, the writing will be adjusted to firm writing. If the controller is twisted in the direction of the "S" (Soft) written on the nib section, the stroke will be adjusted to more flexible writing.
Cartridge/converter filling, converter included. Available in Medium and Fine nibs.