This is one of those things you want to know at the beginning of a home renovation, not at the end. I'm adding RJ-45 outlets for wireless internet access points throughout my house. Half way I discovered these gems. I installed a complete electrical box and punched a few spots in the box to facilitate wire routing to the outlet. This process is painful and I am now finding that it is useless. With these mounts, you cut a hole, stick them in the cutout, bend down the two flanges and screw them in place, connecting the screw to the flange to hold the mount in place until the next millennium. Then all you have to do is insert the keystone into the wall plate and screw it tight. Done at halftime.