These shelves are exactly what I was looking for. I put two units in the closet of a home office. The assembly directions are very clear; it took about an hour and a half per shelving unit. The white crosspieces can be placed so that the shelf sits on top of the piece or sits inside the piece, making a tray.  The shelf itself is very thin (1/4") but because it is supported on all four sides by the rims of the crosspieces, it is very sturdy. Hardware is included to attach the shelves to the wall and to each other. The shelves are open on all sides, so on the inside width I added inexpensive foam board cut to fit to keep the office files upright. I also added a small rectangular piece of wood under each bottom leg to protect the carpet that was in the closet. This price was the best by a lot that I found anywhere. I am 100% satisfied with the shelves and with the experience.