Does anyone remember those triangular shelves that pushed into the walls with a sharp blade?

These triangular shelves were advertised on TV quite a number of years ago. They are for a corner wall and they are very easy to install - underneath the shelf is a "on" you push that pushes 3 sharp blades into the wall. I am wanting to buy some of these and don't know where to look to find them. Any suggestions are very much appreciated. Thank you.