Helemaal onzin. Gaat vanzelf weer los. Blijf daar vanaf. Don't buy them, wherever. I've tried really hard getting the "curved" (more, cap shaped) black ring to align with the display (looks rubbish nonetheless ), got all air bubbles out nicely - and 2 hours later more and more air gets in, until the next day the whole thing falls off. Oh, and I bought two, lucky me. I can be sure it's not a single event. The delivery was good. Product is rubbish.