The clear plastic kept breaking off before I could push them into any surface.

The back plate is transparent plastic, so strong and less obvious.

Because the base is a clear plastic disk, they can even be painted using nail polish if you want them decorated.

They are a relatively thin piece of stiff wire formed into a hook and then pushed through (or molded onto) a clear plastic disk

The clear plastic kept breaking off before I could push them into any surface.

I suppose this is not as bad as if it was too short, but if you are not careful you will likely push these through the backing of the bulletin board