long write joy?

The pins are pleasant when writing ... they glide across the paper and the colors are fun.
BUT: Two of the pins are already empty. I've certainly worked once or twice a week with the pins ... and I'm talking about markers in texts (a few exclamation mark or underline) and maybe 10 flash cards with two words per pin. But now that already do have two of them after 1.5 months limp, let me down. Schade Stabilo.