The oval-shaped Mezrabs (mallets) are feather-weight and are held between the thumb, index and middle fingers. A typical Persian santur has two sets of bridges, providing a range of approximately three octaves. The right-hand strings are made of brass or copper, while the left-hand strings are made of steel. Two rows of 9 bridges[clarification needed] called "kharak."[clarification needed] A total of 18 bridges divide the santur into three positions. Over each bridge crosses four strings tuned in unison, spanning horizontally across the right and left side of the instrument. There are three sections of nine pitches: each for the bass, middle and higher octave called Poshte Kharak (behind the left bridges) comprising 27 notes all together. The top "F" note is repeated 2 times, creating a total of 25 separate tones in the Santur. The Persian santur is primarily tuned to a variety of different diatonic scales utilizing 1/4 tones (semi-tones) which are designated into 12 modes (Dastgahs) of Persian classical music. These 12 Dastgahs are the repertory of Persian classical music known as the Radif.
Similar musical instruments have been present since medieval times all over the world, including India, Afghanistan, Pakistan, Armenia, Turkey, Iraq and Greece, China etc. The Indian santoor is wider, more rectangular and has more strings. Its corresponding mallets are also held differently played with a different technique. The Chinese yangqin and the Greek santouri also derived from the santur. The eastern Europe version of the santur called the cimballum which is much larger and chromatic is used as an accompanying instrument in gypsy music.