I put a link to the one I use down below. But I can't say it absolutely works for prevention. I take it once in a while for prevention and have not had kidney stones again, but I can't say for certain why I have not. Could be diet change, could be the Chanka Piedra, could be I'm going to get them again and just have not to date. But I do take a Chanka Piedra (stone breaker) pill for about three days every couple of months or so. Hope it works. So far so good.

Has good reviews (for whatever that is worth) on Amazon.