Inserts

From CntWiki

An insert is the absorbent part of a pocket nappy. It is the material stuffed into the opening (usually located at the back) of a pocket nappy.

While anything absorbent may be stuffed into a pocket nappy (for example, a terry square), specially made inserts often maximise absorbency while reducing bulk. Some fabrics are more absorbent than others; bamboo and hemp are more absorbent than cotton or microfibre.

Inserts can be customised to suit your baby's wetting (more or less layers of different types of fabric can be added as needed). They can also be removed from the pocket to aid washing and drying times.