I purchased this NEMA L14-30 Emergency Generator Inlet Cover which I have installed in my home. It was the perfect size for the plug. I live in Canada and I also like that it has US (UL) and Canadian (CSA) safety certifications. Two small flaws. First I found that the mounting screws are too short. Aligning the 4 threaded screws in the electrical box can be a bit tricky, longer screws would make assembly much easier (I ended up replacing the supplied screws with longer ones from my workshop). Second, the lid isn't wide enough to cover a standard two-post opening. It would be nice if the plastic backing was as wide as a 2-gang wall board. I measured before I cut a hole in my wall so this wasn't a problem for me, but if you are retrofitting an electrical box that was already installed you will find that this cover is too narrow.