The MICROLINE 420 / 421: 9-pin Impact printers from OKI Proven performance in the most demanding environments. A dedicated forms printer that features 20,000-hours MTBF, and print speeds to 570 cps.1 It prints clearly on 6-part forms. Accepts a variety of media, including multi-part forms, labels and cut sheets Internal Cooling fan reduces the temperature of the print head to maximize throughput during long print runs, and feed rollers ensure precise character placement.