Since the pool cover is telescopic, the inner height is the height of the height of the smallest section and the outer height is the height of the biggest section upper side .
The distance between the inner height and the outer height depends on the section qty, height difference of adjacent sections is about 58.5mm( half round models). So if your pool cover get 5 sections, and the inner height would be about 58.5*4=234 mm lower than outer height.