They fit well. The patterns are adorable. I'm not sure what the official product states, but I have machine washed and dried them many times with perfect results. The padding is adequate without being cumbersome. I would approximate that they hold a regular "pee" without leaking through.
 However I have had them seep through to his pants, if not caught in time (and he was playing/sitting). I bought a 5 pack to start (and bought another brand as weel) but I am buying one more set of these undies. That way I have some clean while the others are in the wash.