Being a woodworker, I don't get to use my angle grinder or flap discs all that often. They do come in handy for cleaning up power carving or doing some minor shaping, but they're really designed for metal.I did have an opportunity to use these on an old cast iron pan that had lost its seasoning and begun to rust. Not only did these clean up the pan, they actually improved the surface quite considerably. What was once a rough, pebbled surface is now shiny and smooth. It's pretty crazy how your nose picks up that weird tangy metal smell at almost the instant the flap disc hits the iron. Lesson learned. You'll definitely want to use a respirator and goggles with these.I can't speak towards the longevity because I have yet to wear one out, but I can say that I used to get my flap discs from the cheapo tools place (you know the one) and these seem to outperform those. Per dollar spent, you're getting a great value here. Plus, they're purple. How can you not like purple?