Charcoal Bamboo/Microfiber Inserts (12 pk) - Each insert is 5 thirsty layers. The outer layers are a Charcoal Bamboo Fleece made from 100% Bamboo fibers and the 3 inner layers are Microfiber which is 100% Polyester. We offer these in two sizes. Size 1 is 4 by 11 inches and is suitable for newborns through about 15 pounds. With this smaller size it is possible to avoid the extra bulk of the typical one size insert while baby is still small. Size 2 is 5 by 13.5 inches and is the typical one size insert. It fits best over 12 pounds but can be used from birth, although it may be slightly bulky for the newborn. These inserts are perfect for adding absorbency to cloth diapers of any kind including pocket diapers, all-in-ones, fitted, prefold and flats. These extra thirsty inserts are perfect for the heavy wetter, naps and nighttime.