I purchased a three-pack of the EarthStone Bathroom stone a few years ago from Amazon. In our previous home, we had extremely hard, city water that would leave terrible rings on the inside of our toilet bowls, despite frequent cleanings. I had tried nearly every product imaginable, and then came across this little gem! It is basically a pumice-stone type of stone that has a little sponge on the other end. It is pretty rough, but somehow manages not to scratch a thing. So, I took this baby to the inside of my toilets - where the terrible rings existed - and got busy. It does take some elbow grease and time, but I was able to scrub off all of the rings from my three toilets using this product. Then, after you get some residue removed, the sponge part is nice to kind of wipe it away. it definitely does take some work, but this is the only product I have ever found that gets the really tough stains off. And what's better - it's a NATURAL product. No chemicals involved! I love it!