If you have to prepare for an exam or just wants to review a result, these mines just right for the ensprechenden pins of Frixion are. Without residue can be removed all that help naturally immensely while learning and folders or leaves do not look so bad smeared out. But beware of tests are not allowed these pins. Delivery was fast and uncomplicated. I use them and my son regularly, for this reason, these mines are depleted relatively quickly.