Germany started a six-month trial run of the much talked about full-body scanners Monday at one of the country's major airports.

Two of the controversial devices were installed at the airport in Hamburg, located in northern Germany, according to Interior Minister Thomas de Maiziere. 

The scanners will be voluntary during the test period. The scanners produce an image outlining the passenger's body to check for any hidden items underneath their clothes.

Airport scanners are already installed in airports throughout Britain. What's more, the U.S. has plans to see 405 of the machines working in airports by the end of the year.  

German politicians have come out strong against the use of full-body scanners, calling them an unnecessary invasion of privacy.