Interior doors self-install standard size or larger?

The two centimeters also seem like a lot to me and I don't like the idea either. It was stated like that in the construction company's documents. However, on the ventilation system's page they themselves only mention 5-10mm. Where exactly do you mean the overflow opening? In the frame? It looked very complicated when I just googled it. The standard size doors cost around €200 together with the frame, etc. The extra charge for 211cm high doors is then about €65.