TierDrop Crystal Clear Sorters are beautiful and functional. Unlike competitive units, TierDrop Crysal Clear Sorters feature clear side, back, and divider panels which let in light, helping you quickly see which slots contain mail. Large compartments accommodate oversized envelopes and small parcels. Models available from 4 to 9 slots. Add-ons also available to increase any 1-Wide Sorter up to 9 levels high. 1-Wide Sorters are ideal for smaller companies or tight spaces.