/diy/ - Do It Yourself

This is a stupid question but I want to know whether this design of wall shelf is strong?
The brown bit is the shelf itself
The grey parts are the supports underneath the shelf
The red parts are plastic caps covering what I imagine to be some kind of screw, each of the supports have a few of them
The reason why I'm asking is because I want to put some very expensive things onto them which would lose their value if the shelf collapsed, I'm a bit paranoid