This is a Lexmark tandem input tray accessory with a caster (wheeled) base, an option that adds high-capacity paper feeding to Lexmark's CX93x/MX93x-series colour and mono production-class multifunction printers. A tandem tray unit typically houses two large-capacity trays side by side, letting a busy print environment go much longer between paper refills than the printer's standard trays allow, and the caster base lets the combined printer-plus-tray unit be rolled into position rather than being a fixed floor-standing installation. This is an accessory sold alongside (not instead of) the printer itself — it doesn't function as a standalone device — aimed at high-volume office or print-room deployments of the CX93x/MX93x series.