In the teens of the 20th century, Sexteto Bolona were one of the most influential performers of son, a vivid Afro-Spanish fusion of musical styles. Son consists of two stylistic levels. The first level (African in origin) is a rumba rhythm over which a variety of percussionists improvise. The second level (deriving from Spain) is provided by a combination of three string guitars known as tres and a makeshift bass. Spanish lyrics are sung over the instruments in traditional decima form with rhymed octosyllabic lines. The group diversified in the 1920s, bringing in Felix Chapotin on trumpet and Arsenio Rodriguez on tres. The group made a departure from traditional son in offering a tighter sound that was influenced by American swing music. The group can be heard on The Roots of Salsa.