I bought 6 of these a few years ago. They work. I thought the concept was great but in reality you have to take the outlet cover off for them to fit properly and that makes them flimsy and not stable. I would not buy them again. Now. If they redesigned them to fit tight against the open outlet and not flop all over the place when plugging or unplugging, I would reconsider. I do like the fact that it makes an outlet into a USB charger and four electric plugs.
Were the receptacles level with the cover plate before installing these? If not, that’s a possibility of why they didn’t fit well.
(FWIW, the cover needs to remain, as it restrains the receptacles from moving around.)