The dressing container was leaking both times at twice use, although a rubber ring to seal located in the lid. The cover of the salad container also dissolves very easily. The fork does not help here as an additional lock.
The cup went back after 2 days. I now have a slightly wider, but smaller plastic box with rubber edge of the lid (1 liter capacity) and a small tin with clip closure for the dressing. Which fits into the salad bowl with in - small, practical, tight.
Conclusion: prefer to use a self-compiled combination.