First of all, the pins are great, they use for several years now and then, especially the way the color "to erase away" is very good, brings but over time a disadvantage, I nicely during my schooldays often realized, namely, the color depending on the storage conditions of the written relatively quickly weaker or can disappear in an extreme case, without which one erases. This is the operating principle of the deletion, the color is heat-sensitive, that is, if you put the written, for example, a book or a notepad on a radiator or anywhere else where there may be relatively warm, the color fades, and depending on the heat it can also be quite invisible. In theory, would have a storage in the freezer reveal the color again, but that works in my experience due to only. Otherwise, it should be noted that the expressions actually becomes empty soon and therefore are not really suitable for everyday use in write-intensive activities. Because of these shortcomings, there is a star deduction. The way through the etching to make the written close to invisible, of course, top and a clear selling point for the pin!
