The levelling course is laid with a drop towards the drain unit at a height that precisely matches the upper side of the horizontal floor flange - neither higher nor lower and is lead right in under the unit so the cavity is filled up.

In this way, optimal support is achieved and fastening of the unit down into the levelling course thanks to the bend on the floor flange.

NB:
The levelling course can be executed in both concrete or with a floor filling compound suitable for this purpose.