tennsco® L & T Four Post Steel Library Shelving is designed for fast assembly...Snaps together in minutes for quick installation and reconfiguration! Unique interlocking keyhole slot design; nuts and bolts are eliminated for obstacle-free access to your books. No tools required for assembly! 18-gauge cold rolled steel frame construction; 22-gauge steel shelves adjust on 1-1/2" centers. Double wall uprights are 24-gauge steel for extra stability. High grade polyester/epoxy powder paint finish. All backed with a Limited lifetime warranty.