A tambora is a percussion instrument, resembling a bass drum

Bass drum

Bass drums are percussion instruments that can vary in size and are used in several musical genres. Three major types of bass drums can be distinguished. The type usually seen or heard in orchestral, ensemble or concert band music is the orchestral, or concert bass drum . It is the largest drum of...

 in Mexican brass bands, mainly in Banda sinaloense and Tamborazo Zacatecano

Music of Mexico

The music of Mexico is very diverse and features a wide range of different musical styles. It has been influenced by a variety of cultures, most notably indigenous Mexican and European, since the Late Middle Ages...

.
It is a double headed membranophone with a diameter of 20 - 26 inches, a fixed cymbal on the frame that is struck with another cymbal and a stand for the drum. A felt mallet is used to beat the drum.