It consists of 10 to 14 tuned metal bars suspended over a tuned resonator of bamboo or metal, which are tapped with a mallet made of wooden disks (Bali) or a padded wooden disk (Java).

There are five notes per octave, so in the seven-note pélog scale, some pitches are left out according to the pathet.

[3] Both types of gendèr play semi-improvised patterns called cengkok, which generally elaborate upon the seleh.

These are relatively fixed patterns, but can be varied in a number of ways to suit the style, pathet, irama, and mood of the piece, as well as the skill of the performer.

Similarly, the gendèr barung is likely to give cues for changing parts or irama, especially in the absence of a rebab, which usually leads the ensemble.