I have bought it twice (and for my grandmother's house). It fits all toilets (adjustable from below). I would say that we don't have very common toilet seats at home. It is not bulky and therefore does not take up space like the ones with a ladder. Until this purchase, our little one did not want to try the toilet. He had rejected everything we had offered. With this and a double step stool, he happily climbed up and the diaper was easily removed. We have it permanently installed and only remove it when we want to use the seat ourselves. So, no supervision is needed in the toilet. He goes whenever he wants.