Very simple. It is dividers, usually made of a strong paper material, but plastic or aluminium foil works too. It must be stronger than cellophane, that won't w

Very simple. It is dividers, usually made of a strong paper material, but plastic or aluminium foil works too. It must be stronger than cellophane, that won't work. Just think about it, if you make a nice slice of bread with strawberry jam, without mellomleggspapir and it would hit right into the slice above and mix with the ham and cheese.