These shelves are awesome!  They secure to the wall via a bar you screw into the drywall, then the shelf slips over the bar.  They angle slightly toward the wall to keep things from sliding off.  My sons love the lights under the shelves to light the top of their desks.  The lights are removable (a slight twist to remove) and you have to add 3 AA batteries per light. The lights tap on and off.  Perfect for over a desk in the corner of a room where you may not have room for a lamp or you do not have overhead lighting.