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. Assembly required.