Double-sided uprights add extra storage density to cantilever systems, allowing you to store long, heavy materials like lumber, extrusions and pipe with good space efficiency and ease of loading and unloading. This 20' model combines with arms and brace sets (available separately), along with any additional uprights that might be necessary, to create the system that works for your materials. Capacity ranges from 39,400 to 50,600 pounds based on arm length.