One-size Nappies are the inner absorbent layer. Because they are One-size-fits-all, they can accompany the baby throughout the nappy changing season. They are suitable for babies between 4 and 15 kg, according to the child's proportions. The size can be easily adjusted by snaps. The nappy absorbency is increased by the so-called booster. One-size Nappies can be found in many different patterns. A waterproof cover to fit over the top is required.