Concept:A customs union is a trade bloc that removes internal tariffs and applies a common external tariff to non-members.
Explanation:Member countries trade freely among themselves without tariffs on goods.
They adopt a unified tariff policy on imports from countries outside the union.
This means all members charge the same tariff on a particular product coming from a non-member country.
A customs union does not require a common currency, free movement of labour and capital, or a common military defence.
Free movement of factors of production is a feature of a common market, not a customs union.
Answer:Common tariffs against non-members.