Udukkai is an hour-glass shaped two-sided drum, commonly used in temples across Tamil Nadu. The two sides of the instrument are covered with stretched skin, which is extremely thin and delicate. On one side there is a thin snare which gives Udukkai its characteristic sound. The body of the instrument acts as a resonator and depending on the material used, the sound quality may differ. Usually, the shell is made of wood and brass. However, it is thought that in olden days, the shell was made in clay.
The two heads of the drum are held together by a continuous rope. A cloth band around the rope is used to alter the tension of the rope, thereby changing the tone of the instrument. The Udukkai is held in one hand and is played with the other.
A variant of the Udukkai, commonly known as Damaru in North India has beads attached to the shell. The instrument is held in hand and sound is produced when the beads hit the head due to the twirling of the wrist. Damaru comes in various sizes and is often smaller than the Udukkai.