The Agung a Tamlang is a type of Philippine slit drum

Slit drum

A slit drum is a hollow percussion instrument, usually a log drum of bamboo or wood, that is made with one or more slits in it. Most slit drums have three slits, cut into the shape of an "H". If, as is usual, the resultant tongues are different lengths or thicknesses, the drum will produce two...

 made of hollowed out bamboo in imitation of the real agung

Agung

The agung is a set of two wide-rimmed, vertically-suspended gongs used by the Maguindanao, Maranao and Tausug people of the Philippines as a supportive instrument in kulintang ensembles...

. Pitch is determined by the length and depth of the slit. The agung a tamlang is used as practice for the real agung

Agung

The agung is a set of two wide-rimmed, vertically-suspended gongs used by the Maguindanao, Maranao and Tausug people of the Philippines as a supportive instrument in kulintang ensembles...

: players either use either one agung a tamlang (hold it with one hand and using the other to strike it with a beater) or using two agung a tamlangs where the other agung is held with one’s feet.