3M (33389) Disc, 33389, 3 in (75mm), 36+, 15 discs per box (Pack of 1)

I’m not sure what they are made of. They last long time and great for cleaning up area.

These things cut better and last longer than anything else I've ever used. They zip mill scale off hot rolled steel better than anything else I've tried as well. I didn't believe the hype but I am converted after trying them. If I remember correctly, I decided to try them after watching a Japhands video on YouTube. Another side benefit is the backing or whatever paper they use is stronger so they don't rip as easily. I sometimes catch the edge of the cheaper ones on sheet metal and rip chunks out depending on the rotation (hopefully that's descriptive enough) but these are thicker and it doesn't happen.I get 3 inch instead of 2 and cut them down to smaller diameter as they wear to last even longer. Trust me get some and try em.They are AGRESSIVE! I haven't tried a lower grit yet but they leave a rougher surface than any other 30 grit I've ever tried. I think it's because they stay sharp all the way to the end of their useful life. If you are looking for a polished surface, try something else or maybe a higher grit. They are for extremely fast grinding and shaping and perfect for smoothing welds. They cut so fast you gotta be careful and even seem to cause less heat.

The box came unsealed inside the packaging. There were only 14 disks.

Last long time and i can cut them down to fit smaller when they wear out on the edges!!!

Works as advertised