The pen works as advertised. We've used it on plastic plant tags and metal orchard tags to good effect.
I use the pen to mark plastic plant labels. So far(approx 1 year), the writing has held up without running.
I really like the nursery marking pen. I live in a plains state, so anything left outdoors is subjected to all types of weather. (This past year especially!) It seems to really stand up to all the elements, and sun fade, and is easily read on my plant tags.
we love them!! they work great, ink lasts in the sun for a long time
Lasts longer than others I've tried.