What We Like About The Lockwood Vertical Mobile Tub CaddyBecause these carts are completely customizable and easily assembled you can order what you need now and add to them as your needs grow. Each column can hold up to 250 pounds amounting to a ve ry sturdy and functional transport for anything you can think of. The aluminum frame is wheeled around on non-marking swivel casters. The vertical design is a beneficial space saver. Customize your storage and organization with different color bins (purchased seperately).Note: to order what is shown - choose the "Tray" option then choose "2" columns. The side rails are adjustable so that you can configure the cart for trays on 1 side and tubs on the the opposite site. This will leave you with e xtra side rails that could be used if you reconfigure the cart at a later time