The DRO-550 PCB is an assembled circuit board that includes all of the surface mount components installed on a professional assembly line.  This includes the ARM7 processor, the on-board power regulators, the switches, scale interface circuitry, and the LED display drivers.

You will need additional parts to complete your DRO-550 system including the LED displays, headers, case, cables, and overlay.  See the DRO-550 product pages for more information.