The Surdos are the heartbeat of the samba reggae band. The "boom-boom", provides the foundation for the band's rhythm. The biggest surdo, a surdo 1, or the primeiro, plays on beats 1 & 3. The Surdo Segunda (2) or Resposta (meaning response) responds to the First Surdo & plays beat 2 & 4. Together these are called Marcacao (meaning “marking” as in “marking time”), because they mark the beat.
Smaller in diameter than a standard surdo, the dobra plays syncopated "off-beat" rhythms that cut between main beats to create the band's signature sound and lead the choreography.
The repinique (also known as the "repi") is a small, high-pitched drum that drives the fastest and most complex rhythms in a Batala band. Because it produces a sharp, piercing sound, it is also frequently used by section leaders to call breaks and signal rhythm changes.
The caixa is the engine of the band. It is a traditonal snare drum and provides the constant driving energy. It is similar to the snare found in a rock band.