The 2 euro coin (€2) is the highest-value euro coin and has been used since the introduction of the euro (in its cash form) in 2002. The coin is used in 22 countries (with 20 legally adopting it) with a collective population of about 341 million. The coin is made of two alloys: the inner part of nickel brass, the outer part of copper-nickel. All coins have a common reverse side and country-specific national sides. The coin has been used since 2002, with the present common side design dating from 2007.