There is a broad list of prohibited things for air freight, and it varies by country legislation and airline restrictions. These forbidden objects consist of the following, with less obvious instances in brackets: gases (e.g. lamp bulbs) (e.g. lamp bulbs) ; all flammable objects (e.g. perfume) ; corrosive or poisonous substances (e.g. batteries) ; magnetic materials (e.g. speakers) ; dangers to public health (e.g. untanned hides) ; Biochemical products and oxidizers (e.g. chemical medicines) ; something whose package bears a warning symbol.