I skeptically bought a pack last week to refinish a piece of furniture....150 grit. So far I am pleased with ease of use and effectiveness. Lots of coves and beads and the paper, make that product, handles them very well. Ah heck, I'm still gonna call it sandpaper. I can't comment on the 15x as I've never really tried to see how long sanding material lasts. I would buy again.