"► Field Upgradeable Serial Module\n► You cannot get the serial module preinstalled with your printer at purchase.\n►Important: This is not backwards\ncompatible with the ZD420\n► Compatible Printers: ZD421D, ZD421T,\nZD421C\n"
"► Field Upgradeable Serial Module\n► You cannot get the serial module preinstalled with your printer at purchase.\n►Important: This is not backwards\ncompatible with the ZD420\n► Compatible Printers: ZD421D, ZD421T,\nZD421C\n"