Review on Toilet Cleaning Pumice Stone Set with Handle and Holder (2 Pack) - Stain Remover for Toilet Bowl, Limescale, Rust, Bathroom/Kitchen Sinks, Grill, Porcelain - Toilet Wand Brush by Karla Richter

This thing is amazing. I opened it *immediately* after it arrived and immediately got to work on the hard water stains in all three toilets. Rings unresponsive to half a dozen other "industrial" cleansers and scrubs vanished with about the same effort as brushing your teeth. You can even feel the buildup of hard water before you see it; I went all over the inside of the shells and the cleaned areas seemed perfectly smooth while others looked a bit grainy on the pumice stone. I would highly recommend and will definitely be ordering more.