Paila criolla was initially used by street bands in the 19th century. They are shallower in shape than single-headed tom-toms, and come in double sets, tuned an octave apart. The player (known as a timbalero) uses a variety of stick strokes, rim shots, and rolls on the skins to produce a wide range of percussive expression during solos and at transitional sections of music, and usually plays the shells of the drum or auxiliary percussion such as a cowbell (cencerro). Pailas are always hit with straight batons that have no additional head. Hits are made on the top and on the metal sides.
The shells are referred to as cáscara (the Spanish word for shell) which is also the name of a rhythmic pattern common in Cuban music that is played on the shells of the pailas to keep time. The shells are made of metal. The heads are light and tuned fairly high for their size. Pailas are now often called timbales, but the term timbales is ambiguous, because it was also used to describe kettle drums.
Although the term timbal or timbales (pl.) is often used now to mean pailas, there is a problem with this usage, because timbal has been used in Cuba for two quite different types of drum. In the first place, it was first used to describe the kettle drums used in the wind orchestras known as Orquesta típica. These were the same general type of drum used in military bands, perhaps slung either side of a horse, and in classical orchestras. These were, and are, played with sticks which have softish round heads.
The orquestas típicas were gradually replaced early in the 20th century by charangas. The general idea of the charanga was to replace the wind instruments with violins and flute to bring a brighter, lighter tone to the band. The typani were replaced by pailas criollas, which because of their light weight were originally used by street bands. Pailas were taken over by the early charangas; their original name is still used in Cuba, but over time the familiar term timbal has been taken over to describe the pailas. There is often a second set of even smaller drums, timbalitos (= pailitas), which produce an even higher note when struck. In a modern band the timbalero may also have a trap kit as an alternate for certain numbers.
Thus the term timbales is ambiguous, particularly when referring to bands playing the danzón in the 1900-1930 period. If one does not have a photograph it is difficult to know which type of drum was used by the band.