Magnesium is very active in the air, please carefully read the MSDS Here and open the package in glove box with inert gas and moisture less than 2%RH.
Shipping Limitation
Note
MTI only sells Magnesium ( Mg ) Foil within the US and does not accept international orders in order to comply with the restrictions on hazard material exportation!!!
Shipments of Magnesium foil are described as "UN 1869, Magnesium, 4.1, PG III".
All shipments are Hazard Class 4.1 and require “Flammable Solid” label.