As a "tip" to the newcomer when it comes whiteboards are, I noticed in the months of use, the following aspects: Keep tilted the marker - essentially like a real pen, and not as a chalk - and write with the flat edge of the tip. This significantly increased for me the life of the pins. If you hold it vertically, so the tip is namely soft, with the corresponding consequences as everyone can imagine. Furthermore, the pin should be empty, use Nachfüllfässer, and leave the pins permanently stuck in the barrel, so that they are always full.
Overall, a very useful, durable, reusable product, very good for a price in my opinion. The Nachfüllfässer are correspondingly cost, considering how long they hold - with me many weeks, in spite of intensive daily use.