Our prefolds are made of 100% Unbleached Indian Cotton. These twill weave diapers are incredibly soft and absorbent and become softer with each washing. You will need to wash them a few times in hot water to remove the oils and make them absorbent. As with all cloth prefolds these will shrink 5-10%.Infant 4x8x4's and 15 1/2" long fit babies 7-15 lbs and are the thickest most absorbent infant sized prefold. There are 4 layers of cotton on both sides and 8 layers in the middle. The infant size is great to use as a doubler or stuffer for pocket diapers after your baby outgrows this size. Regular 4x8x4's and 21" long fit babies 15-30 lbs. There's no need to use pins with our prefold diapers. Simply fold the diaper into thirds and set it into one of our diaper covers or stuff it into a pocket diaper. If you would like it to be more fitted then, use a Snappi Diaper Fastner. Below is a great link to an illustration of how to fold a diaper inside a Bummis Wrap Diaper Cover.