Great product!
We are on a well, therefore, over time a ring builds around the bowl.  I've tried many products to no avail.  I used this product within an hour of my Amazon delivery.  The instructions says don't turn off the water to the toilet.  I did turn off the water and flushed to empty the bowl to fully expose the ring.  I squirted the ground pumice gel  onto the non-scratch patch that was provided.  I made small circular patterns on the ring.  Voila!!!!!  Ring disappeared.  I turned the water to the toilet back on, let the tank fill, and flushed.  It worked GREAT!  The effort was not great at all, just press while making little circular motions.  I highly recommend this product.
Rating: 5 stars