When entering China, visitors are entitled to a duty-free allowance of 70 fluid ounces (2 liters) of wine or sprits, 400 cigarettes, and a certain amount of gold and silver. Foreign currency exceeding US$5000, or its equivalent, must be declared. Items that are prohibited include fresh fruit, rare animals and plants and arms and ammunition. Chinese law specifies limits on the export of certain items, such as herbal medicines. Also, objects predating 1795 cannot be taken out of China, while antiques made after that date will need to have an official seal affixed. Although foreign visitors are largely left alone, it is not advisable to take in politically controversial literature, especially to sensitive areas such as Tibet where there have been instances of books being confiscated.