We have a tall, skinny 2 year old and most pants that are long enough are WAY too big in the waist to stay on his little behind.  I lamented the idea of him wearing a belt, especially since we are potty training, plus they make me nervous because he could take it off and... (insert paranoid delusion here).  These keep his pants up, never come off/loose/undone, and makes potty training a breeze since there's no belt!  Awesome product.