Sturdy Mail Sorters made of 5⁄8" compressed wood with adjustable hardboard dividers. The 36 Compartment Sorter has large sorting slots to accommodate over-sized envelopes. Stack up to two high to increase sorting capability. Black plastic molding does double-duty, first as an attractive accent to the finish and second as a label holder for identifying the bins (labels are included). Durable laminate finish will compliment any setting. Solid fiberboard back provides stability for the unit. Quick and easy assembly.