USB fingerprint scanners (i.e. Hamster IV, Hamster Plus) help you capture fingerprint images. These devices get plugged into the USB port of your computer. In order to use these devices in your application, you need legacy driver. It allows scanners to communicate with your computer. Usually Hamster IV or Hamster Plus fingerprint scanner devices come with 2 types of drivers, the legacy driver or the Windows Biometric Framework (WBF). The Legacy driver needs to be installed manually when you plug in the scanner on to the computer. If the legacy driver is installed on Windows 7 or later computer then there is a chance that the driver will be over-written by the WBF driver= during Windows updates. To avoid this, please update the SDK dll, for example, sgfplib.dll (from FDx SDK Pro).