Hi Tae,
You do not need a shield.
In the pdf found at the following link, see chapters 9-12 for the MTUKD2 and chapter 13 for the MTMDK.
http://www.multitech.com/documents/publications/manuals/s000612.pdf
MTMDK
http://www.multitech.com/models/94558020LF
MTUDK2
http://www.multitech.com/models/94558010LF
Kind regards,
Leon