The SAGEM Fst 800-840 is an ADSL modem used for broadband Internet connections. It's a device that connects your computer to the Internet through a DSL (Digital Subscriber Line) connection, usually through a phone line. The Windows driver for the SAGEM Fst 800-840 ADSL modem enables your computer to communicate with the modem for proper setup and operation.

The driver for the SAGEM Fst 800-840 ADSL modem is essential for ensuring that your computer recognizes the device, whether you are using it via USB, Ethernet, or other connection methods supported by the modem.