Garybank Set of 3 Mezuzah - Pewter Mezuzahs with Scroll for Door, Jewish Gifts, House Warming Blessing, 5.31 inch/13.4 cm

Will they rust?

I received these metal mezuzahs and they each come with a thin piece of plastic that looks like a cell phone screen protector, what are these plastic

Where is this made?

If a room has two entrances, am I required to affix two mezzuzahs or one?