So I waited 3 months before writing this review to see how well they worked. I can honestly say I am pleasantly surprised at the results. I normally have horrible hard water stains that appear after a week or 2 of scrubbing them off. After 3 months of dropping these in my tanks, they have not re-appeared! My toilets look amazing. I was hesitant to spend $99 for all three of my toilets but this product is well worth the money. I would highly recommend them if you suffer from hard water stains!

I was skeptical, but this works, 2 weeks in and no ring. We have very hard water where I live and this is a blessing in fact I’m ordering my 3rd one.

Well, so far so good! I've had KK in for about 3 weeks now. No water rings! Of course you still have to "clean" the toilet but it's much easier now.
I'm glad I decided to get one for each toilet.
Thanks Krazy Klean!

So far so good I bought 3 of these and they all work just fine they keep all my toilets Very Very clean

The toilet tank is "crystal clear" no hard water build up at all, and the water line in the bowl is gone!