Welded six-shelf bookcase is reinforced for durability. Extra strength is added in the welding process, providing years of heavy use. Shelves have multiple bends at front and rear for additional strength and maximum rigidity. Exposed bolts are completely eliminated for a clean professional appearance. Tops have no overhang so side-to-side units will fit flush together. Durable shelves are designed tough. Each shelf is capable of supporting 120 lb. Adjustable shelves adjust vertically in 2-5/64" increments to accommodate materials of almost any size. Shelves can also be adjusted on 12-1/2" centers that are clearly identified so they are perfect for binders. Built-in shelf support tabs mean no clips to lose. Double bottom provides extra strength and allows easy retrieval of materials.