Snap-In-Ones (SIO) are a type of all-in-one or complete nappy. The only difference is that the insert is not sewn in, but can be buttoned in and out again with snaps. This way, if the insert gets just a little wet, you don't have to wash the whole nappy right away. The nappies come with one insert, additional inserts are available separately. If the child usually makes a lot of pee at once, it is usually necessary to wash the whole nappy.
If Snap-In-Ones (SIO) are to be used continuously, we recommend 10-15 nappies plus 10 extra absorbent inserts made of bamboo or hemp. Snap-In-Ones are available from the manufacturers TotsBots and Petit Lulu. The inserts of the pop-in nappies are also attached with snaps. However, we count them as All-in-Ones. They have an absorbent core in the middle of the overpants and if it gets wet, the entire nappy needs to be changed.