The entire unit is made of industrial strength steel. It is sturdy and tough so it does not wobble. It is also lightweight compared to wooden shelves our pieces can be handled all by one person. Theses Shelves are fully adjustable and configurable, because you can add as many shelf levels and add-on units as you can fit in your space. The units are very pleasing to the eye. Completely smooth shelf levels make it easy to slide items around, not wire grid shelving which can snag easily. There are 6 metal shelves, each for $10