This program, for Macintosh users, will allow you to change the firmware type of your Zoom PC Card 56k modem from K56flex into V.90 (V2.100), and vice versa. The change can be made only if you have a Zoom K56flex PC Card Data / Fax (nonvoice and non-Dualmode) modem. If you are unsure of your PC Card modem type, follow the instructions in the readme file included with the upgrade.