Ink cartridges are not easy to find or I haven't found them. The bookstores have something similar in length that doesn't fit.

Very practical pen. Excellent quality of the plastic parts. Good colors that can be changed when they run out. The pencil mechanism is stable and efficient. It is a solution where you can have 3 pens and a pencil without carrying a pencil case. I recommend it!

Tool for the teacher. Pencil worth every penny. The downside is that when the blue - usually - runs out, its usefulness decreases. Spare parts cannot be found in the inks or I don't know where to find them.