This bed rail is one of the most annoying, useless things I have ever bought for my son. We've had several bed rails as he's a very active sleeper, and all the others we've used (Babydan has been the best) have worked and fitted on numerous beds. We have just moved him into another room as he has a baby sister arriving soon, so ordered a new rail, as the sister will get the old ones on our bed.
This rail has ridiculous ball shaped corners which either mean the mattress is nowhere near the rail, or that it is horribly bent in order to fit inside a very ordinary bed frame. I can see this working, perhaps, if you have a divan bed. If not this isn't remotely suitable and is definitely not going to fit on "most bed frames".
On top of the bad design, the rail is over engineered. A babydan rail arrives in two parts that you click together. The box for that rail is tall and thin. This arrived in a shorter but fatter box, but in about twenty different pieces that have to be clicked together with annoying ball bearings that really hurt your fingers. We put it up, tried it, took it down, and returned it immediately. We ordered a white, wooden babydan rail instead for a few extra pounds. It's just arrived, up in minutes, and the extra money is more than worth it. It also looks a lot nicer.