All racks are constructed of heavy-duty, power-coated steel for long-lasting durability and strength. 5- and 10-Ball Racks tout all-welded construction for superior strength. 3-Tier Rack holds 15 balls and presents a narrow profile and lockable casters for easily rolling room-to-room. 4-Tier Rack gives easy access to 22 balls anywhere, with rotating racks and lockable casters for 360 degrees of convenience. Oversize Ball Rack has stronger tubing and is wider all around to accommodate larger balls and heavier weights. Assembly required.