I have one thing to say: there are wall plugs, and then there are fischer Duopower! A completely different category from anything else out there, even the big brand names. I wonder what I was doing with my life before I bought them and struggled. I didn't believe that the screw could tighten so much; usually, if you tighten the others too much they just spin crazily, but this one doesn't move at all, even with a power screwdriver, it's completely locked. Not a single one has failed, they have a 100% success rate in tightening and holding in any material. It gives you the impression of safety, that whatever you fix will never move (not even a millimeter) from its place. I've now replaced all the old wall plugs I've installed in my house, and whenever a handyman comes to do some installation, I give him my own to use. As for the price, they're expensive but worth every cent. You'll get the job done with 100% safety, 100% success, forever..!