As a do it yourselfer I find that when driving in the nails to hold these outlet/switch boxes they tend to slide a little. So when you hang the drywall the box is not flush making finishing and outlet covers difficult to install. These units solve the problem. With the metal it is hard to goof up when driving the nail so that the box will not be tilted or to far out or in.Another aspect is you can screw it so it is flush with the backside of the drywall. Then you chalk the box and hold the drywall in place for a second and you have a perfect outline for your cutout. Cut out hang the drywall and screw out the box to be flush with the front face of the drywall. The time savings alone makes it worth the added cost.The only gripe I have with these is, it seems the plastic is a bit more brittle than other ones I have used in the past. I broke a small corner of of one when I missed the nail with the hammer. Of course, I am the only one who misses a nail every now and then! I will purchase and use these again in the future.