Our little one is sleeping in the morning not so long when some sun already shining in his room. So we wanted to darken his window. Since its window is very large, we could use the whole film in entire size. Result: film darkens and the little sleep (great!). On vacation, we have also taken the film. Since the window was not quite as big and we had to shrink as the instructions say. Somehow this becomes a very beautiful Gewurschtel, so that the film wrinkles beats and the weight is also not so good held by the suction cups: Result: film drops. Otherwise, it's really in the room pitch black when the film's turn! The manual could be a little more detail.