The official currency is the Czech Crown, locally known as the Koruna (CZK), which is divided into 100 haler. Most credit cards, including American Express, Diners Club, Visa and MasterCard are accepted, but it is best to have cash handy when travelling outside of Prague and the main tourist centres. Foreign currency can be exchanged at banks, bureaux de change and some hotels; commission is highest in hotels. Banks are closed on weekends. ATMs (known as 'bankomats') are now common in Prague and are probably the best way to obtain local currency at a good rate. The Czech Republic is still cheap compared to the rest of Europe, though the gap is closing.