The Tennsco Z-Line Boltless 36"W Shelving Adder Unit with Particle Board Shelves assembles easily, without the need for nuts and bolts. The corner posts have tapered keyhole slots that are 1 1/2" apart, making it easy to adjust the height of shelves. The industrial-grade 5/8" thick particle board shelves allow for maximum accessibility and hold up to the toughest situations. For smaller item storage, add extra shelves (sold separately). The 16-gauge cold rolled carbon steel frame is electrostatically powder-coated for durability. Attach to an existing starter unit to extend your shelving space.