In Mexico , a maquiladora ( Spanish pronunciation : ( makilaˈðoɾa ) ) or maquila ( IPA : ( maˈkila ) ) is a manufacturing operation , where factories import certain material and equipment on a duty - free and tariff - free basis for assembly , processing , or manufacturing and then export the assembled , processed and / or manufactured products , sometimes back to the raw materials ' country of origin . They are an example of special economic zones as seen in many countries .

Question: factories that assemble parts made in other countries
Answer: special economic zones