Breakthrough nib design features two parallel plates that create sharp, beautiful lines Parallel Pens come in 3 nib widths, each packaged separately: 2.4 mm, 3.8 mm, 6.0 mm Mixable inks create remarkable color effects by blending the ink of two pen nibs Each pen comes with two cartridges, a converter, nib cleaner and instruction booklet Mixable Colour ink cartridges- 12 - formulated for the parallel pens.