The Shruti box is a very popular instrument for Hindustani classical singers, religious ceremonies, and other musicians looking for a simple drone sound to accompany their music. It is essentially a keyless version of the harmonium, equipped with 9 drone sounds.
It is played by opening and closing the various drone stops to manipulate the airflow of the box and squeezing air into the 2 alternating pumps located on opposite sides of the box. The double bellow side is pressed first by using the forefingers, expanding the single bellow side which is then pushed in with the thumb. Lightweight and portable, the shruti box is made of rosewood and comes with a carrying handle.