According to leading German consumer test Stiftung Warentest Bett1 provides the best Internet mattress. And I like them. But no two copies of the mattress seem to be the same. One of the mattresses below is already an exchange mattress. The previous one had a different height than left one. These two at least have the same height, but are of different length (officially, both are 200x80cm). Go figure.
The mattress cover is removable (already removed above) and so I matched the lower cover from one mattress with the upper cover from the other mattress. Quite a difference, how annoying.