The "son", said Cristóbal Díaz, is the most important genre of Cuban music, and the least studied. It can fairly be said that "son" is to Cuba what the tango is to Argentina, or the samba to Brazil. In addition, it is perhaps the most flexible of all forms of Latin-American music. Its great strength is its fusion between European and African musical traditions. Its most characteristic instruments are the Cuban guitar known as the "tres", and the well-known double-headed "bongó"; these are present from the start to the present day. Also typical are the claves, the Spanish guitar, the double bass, and early on, the cornet or trumpet and finally the piano.