: Check the boxes for "Flashmode Drivers," "Fastboot Drivers," and the specific model-based drivers for your device.
: For newer devices, Flashtool may require an FSC script. If missing, the tool may default to older flashing methods which might not work for 2015+ models. download link for a specific Xperia model, or do you need help fixing a "device not found" error in Flashtool? How to flash your device - Sony's Developer Portal
The Driver Pack is a bundled installer containing the necessary USB drivers for almost every Sony Xperia model. While official Sony tools like Xperia Companion provide standard connection drivers, FlashTool requires specific and Fastboot drivers to perform deep system modifications.