They don't work as well as I was hoping they would. My mattress still slides around on my metal bed frame, it's just not as far as it was going without these on it.These fit my bed pretty well and keep the mattress from sliding. It still slides a little bit, but that's more due to the dimensions of my mattress. I might stick a piece of foam between the bracket and the mattress to make the fit tighter.One caveat. There is a ridge on the inside around where the screw hole goes thru. The first time I tried this on the bed, that screw hole scrapped the paint off the bed frame. Luckily it was on the inside of the side rail where it wasn't visible. I wanted to put the bracket on the opposite way to hold the mattress better, so I used a small needle file to file off that ridge, so it wouldn't scrape the paint off the bed frame.This may work for some but not for what I wanted. I also ordered one size and was sent two different sizes. I returned.Product was exactly what I wantedThe half-inch models work perfectly with the heavy-duty version of the Zinus SmartBase, where mattresses are more prone to slipping than on the models with wire supports. Mine didn't come with screws, either because the shipment was off or they aren't included with that size, but they haven't been necessary in any case as the fit is very snug.If you have a platform bed frame this will not work very disappointedI do like the idea of these, but my mattress is constantly sliding up over them. The screws are to short to keep them in place. When changing the sheet on the bed, they fall off.I wish they were higher so the mattress would stay on better. The screws need to be longer. Other than that they do work for keeping the mattress from sliding off to the side.These were heavy duty steel & sturdy. Really nice. But! Problem: I measured my bed frame to the "T". According to the product description, the measurements should have fitted perfectly & a little loosely according to my measurements. Well, I could get it over the frame nor the narrowest little metal bar on the frame. The mounts are weird. They are missing screws & an additional bracket that goes with this type of mattress retainer. But, I took for granted that it automatically came w5the mounts. No worries, though. They were too small & measurements inaccurate.Be very cautious buying them. Evidently, they're made to fit bed springs, because it sure not going to fit the narrowest frame. Once Again, Amazon Customer Service Agents cane to the Rescue! I just love those Amazon Agents! ???