Here is the list of country codes used by Apple devices.
MB123XX/A or MC123XX/A is the device code and XX is the regional identifier (or however it is called).
This code you can find in this list:
AB Egypt, Saudi Arabia, United Arab Emirates
B Ireland, UK, also used for some replacement phones
CZ Czech Republic
DN Austria, Germany, Netherlands
FB France, Luxembourg
FD Austria, Liechtenstein, Switzerland
KS Finland, Sweden
LA Colombia, Ecuador, El Salvador, Guatemala, Honduras, Peru
LZ Chile, Paraguay, Uruguay
NF Belgium, France, Luxembourg
SO South Africa
X Australia, New Zealand
ZP Hong Kong, Macau