Public Shared Function GetSerialNumber(ByVal DriveLetter As String) As String
 
        Dim wmi_ld, wmi_dp, wmi_dd As ManagementObject
        Dim temp, parts(), SRN As String
 
        SRN = ""
        wmi_ld = New ManagementObject("Win32_LogicalDisk.DeviceID='" & _
          DriveLetter.TrimEnd("\"c) & "'")
        For Each wmi_dp In wmi_ld.GetRelated("Win32_DiskPartition")
            For Each wmi_dd In wmi_dp.GetRelated("Win32_DiskDrive")
                temp = wmi_dd("PnPDeviceID").ToString
                If Not temp.StartsWith("USBSTOR") Then
                    Throw New ApplicationException(DriveLetter & " Kein USB" & _
                      "Laufwerk")
                End If
                parts = temp.Split("\&".ToCharArray)
                SRN = parts(parts.Length - 2)
            Next
        Next
 
        Return SRN
 
    End Function