1. LA-4121 PC Card Adapter
2. LA 4123 PCI Adapter
3. LA-4137 Wireless Networker CompactFlash CF Card

According to the release note, for the LA-4121 and LA-4123 adapters, the driver will automatically update firmware to the most recent version. For the LA-4137, the firmware is integrated into the driver. Includes Mobile Companion Utility v. 3.9.2.45; Driver v. 3.9.71.178; integrated LA-412x Firmware v. 2.92-58; integrated LA-4137 Firmware v. 3.9.2-71.

Instead of linking to the driver file directly, the download link will take you to Symbol Wireless Networker CompactFlash and LA-4121 PC Card Documentation & Drivers page, where you can also read and download on other older drivers such as:

1. PocketPC Drivers and Utilities for Wireless Networker CompactFlash and LA-4121 PC Card Formats.
2. Pocket PC 2002 Driver and Utility for Wireless Networker CompactFlash and LA-4121 PC Card Formats
3. Handheld PC 2000 Driver and Utility for Wireless Networker CompactFlash and LA-4121 PC Card Formats
4. Linux Reference Driver For the Wireless Networker CompactFlash Format

Alternatively, you can try the Free Driver Scanner.