type
   STORAGE_QUERY_TYPE = (PropertyStandardQuery = 0, PropertyExistsQuery, PropertyMaskQuery, PropertyQueryMaxDefined);
   TStorageQueryType = STORAGE_QUERY_TYPE;

   STORAGE_PROPERTY_ID = (StorageDeviceProperty = 0, StorageAdapterProperty);
   TStoragePropertyID = STORAGE_PROPERTY_ID;

   STORAGE_PROPERTY_QUERY = packed record
      PropertyId: STORAGE_PROPERTY_ID;
      QueryType: STORAGE_QUERY_TYPE;
      AdditionalParameters: array[0..9] of AnsiChar;
   end;
   TStoragePropertyQuery = STORAGE_PROPERTY_QUERY;

   STORAGE_BUS_TYPE = (BusTypeUnknown = 0, BusTypeScsi, BusTypeAtapi, BusTypeAta, BusType1394, BusTypeSsa, BusTypeFibre,
      BusTypeUsb, BusTypeRAID, BusTypeiScsi, BusTypeSas, BusTypeSata, BusTypeMaxReserved = $7F);
   TStorageBusType = STORAGE_BUS_TYPE;

   STORAGE_DEVICE_DESCRIPTOR = packed record
      Version: DWORD;
      Size: DWORD;
      DeviceType: Byte;
      DeviceTypeModifier: Byte;
      RemovableMedia: Boolean;
      CommandQueueing: Boolean;
      VendorIdOffset: DWORD;
      ProductIdOffset: DWORD;
      ProductRevisionOffset: DWORD;
      SerialNumberOffset: DWORD;
      BusType: STORAGE_BUS_TYPE;
      RawPropertiesLength: DWORD;
      RawDeviceProperties: array[0..0] of AnsiChar;
   end;
   TStorageDeviceDescriptor = STORAGE_DEVICE_DESCRIPTOR;

const
   IOCTL_STORAGE_QUERY_PROPERTY = $002D1400;  

var i: Integer;
   H: THandle;
   USBDrives: array of Byte;
   Query: TStoragePropertyQuery;
   dwBytesReturned: DWORD;
   Buffer: array[0..1023] of Byte;
   sdd: TStorageDeviceDescriptor absolute Buffer;  

begin
   SetLength(UsbDrives, 0);
   SetErrorMode(SEM_FAILCRITICALERRORS);
   for i := 0 to 99 do
   begin
      H := CreateFile(PChar('\\\\.\\PhysicalDrive' + IntToStr(i)), 0, FILE_SHARE_READ or FILE_SHARE_WRITE, nil, OPEN_EXISTING, 0, 0);
      if H <> INVALID_HANDLE_VALUE then
      begin
         try
            dwBytesReturned := 0;
            FillChar(Query, SizeOf(Query), 0);
            FillChar(Buffer, SizeOf(Buffer), 0);
            sdd.Size := SizeOf(Buffer);
            Query.PropertyId := StorageDeviceProperty;
            Query.QueryType := PropertyStandardQuery;
            if DeviceIoControl(H, IOCTL_STORAGE_QUERY_PROPERTY, @Query, SizeOf(Query), @Buffer, SizeOf(Buffer), dwBytesReturned, nil) then
               if sdd.BusType = BusTypeUsb then
               begin
                  SetLength(USBDrives, Length(USBDrives) + 1);
                  UsbDrives[High(USBDrives)] := Byte(i);
               end;
         finally
            CloseHandle(H);
         end;
      end;
   end;
   for i := 0 to High(USBDrives) do
   begin
     //
   end;
end.