Heavy duty plastic construction outlasts cardboard alternatives. Will not sag or bow. Holds up to 15,000 sheets. Integrated label holder on each compartment. Each slot measures 9.5' wide x 12' deep. Combine several units to make up to 72 compartments. An add-on unit is available to increase the capacity of this unit. SKU STX 61417U01C upc 685442614178. Can also be used as an sorter for 9'x12' construction paper.