, it is usually only for enabling the "auto-switching" feature (detecting data flow) or for a software-based switching utility (instead of pressing a physical button).
Gaintech has multiple variants (e.g., GUH2S4, GUH2S2). Look for a sticker on the device. The driver depends on the internal chipset, not the "Gaintech" brand. gaintech usb 2.0 auto sharing switch driver
Older units shipped with a tiny CD. The driver on it is likely for . , it is usually only for enabling the