I bought that exact thing when I first started lifting. They're not very stable, and over time they get worse and worse. Ended up getting rid of them altogether.

This time I bought a similar product but with a connector in the middle, the bottom welded to the floor supports, and a slanted brace behind the support bars. It doesn't rely on nearly as many bolts and doesn't have as many places where it can twist under weight, and it's done me well so far.