Review on Professional Whetstone by Donxote Sharpening by Jesus Jenkins

I'm not an expert so I can't tell you why, but 400/1000 grit stones wouldn't remove even the slightest amount of metal from an edge. I sharpened them aggressively for a while just to see if I could make a mark in the metal and I couldn't as if they were rubber. So 400/1000 is useless. As for the 3000/8000, they really removed the metal. The 8000 dulled the knife quicker than the 3000 (I've used knives of the same make and model that dulled equally on both) so I'm guessing the 3000/8000 grit is definitely very different. I may have come across a poor quality batch but still my advice is if you don't want to risk returning them or wasting your money try a higher quality brand.