Finally my negative strips have found a secure "storage vehicle". The award is for the amount of cases in order; nice, I think the added paper sheets per envelope, which scatters the light and the "glancing through" help. The strips are held securely in their slots. Although everything seems a little delicate, the casings are surprisingly robust.
The casings can be archived in the corresponding Hama prima folder that is a bit expensive. For beautiful Negative - usually quite old memories from pre-digital times - you should however the treat; it is money well spent.