This plastic clip works much better than the old little metal clips that came with the shelves 10 years ago--they offer more support.
However, they do not help at all with the issue we have had of the holes into which they go--over time with weight of books bearing down on the supports, the holes have become enlarged. None of the clips have the tight fit and the shelves keep falling down.
We had to call a handyman to drill new holes to solve that issue. But over time, these holes may also become enlarged. The solution would be to have thicker stems and more supportive clips, and perhaps thin plastic sleeves to go over the stems to increase the thickness to accommodate the enlarged holes.