I have been using the cans for about 8 years and find you can write even on a board with the ink pen and it works. Also if you will bend the point instead of cutting it off you will find it will be sturdier when you put it in a stubborn pot. I also snip a small hole in the end to tie to taller plants and hay bale string works great. If you are using temporary tags like one or 2 years you can cut up a bleach bottle and use a permanent marker pen to write you information on.
I also cut the label from bottom to top for the strips ...it makes more labels