The new plastic base will not seal to 4-inch exterior boxes. The screws holding the crosspiece stop the rubber insulator from sealing with the box. I had to take the rubber seal from the discarded metal base to fill the gap between the rubber seal on the plastic box and the 4-inch metal box. Also, one of the mounting posts for the floodlight/camera cracked when I pulled it down tight enough to seal the gaskets and prevent rotation. Please return to the metal mounting plate or redesign the new plastic plate so that it is more robust and will seal tightly.