These covers fit my 9 lb newborn perfectly over both fitted and prefold diapers and sit right under the cord stump. The covers are extremely high quality and the aplix is both easy to use and strong. I can tell they have plenty of growing room and they will last up to the listed 13 lbs and beyond.
These were okay for my 7lb NB. The covers did not grip her leg as well as the rumparooz NB covers, so I had a few blowouts; and also had occasional wicking from the prefold inside, even when I did my best to tuck it in all the way. More rumparooz would have been better, instead of these.