As I always start with my reviews, I bought this product with my own hard earned down jackets because I needed larger grinding parts for my powerful wood carving. I didn't get this as a promotion or for free. (which sucks because I would take any of them and write my honest opinion anyway). Anyway, here's what I got: 50 very well made grinders with a few caveats. 1) There were a few pieces that were slightly skewed from the 90 degree shaft. This means they will flutter slightly in a rotating tool and therefore will not stay perfectly flat when ground. I found it mainly in 2 large square thick round pieces (to the left of the description image) and 2 smaller rounded edges. I also found that there was almost no diamond dust left on the two spherical ridges, which becomes a problem with any engraving (even on wood). So what happened?: I contacted the seller and they fixed the issue almost immediately. problems are solved. Can I recommend this product? Yes why because when you look there seems to be only 2 sellers shipping this product on Zon and I really like this one. You have my return business! Hope this helps someone on the fence. If you're going to use it for mechanical wood carving, I also recommend looking for a 60 grit bit set. They cut through soft wood for great detail. Regards, -A