The santur (سنتور – also santūr, santour, santoor) is a hammered dulcimer of Iran. It is a trapezoid-shaped box often made of walnut, with 72 strings. The name means one hundred strings in Persian. The special-shaped mallets (mezrab) are lightweight and are held between the index and middle fingers. A typical santur has two sets of bridges, providing a range of approximately three octaves. The right-hand strings are made of brass, while the left-hand strings are made of steel.Two rows of 9 articles called "Kharak" (Totally 18 kharaks) divide Santur into three positions and each lead four unitone strings to the right and left side of the instrument . Each note comes three times in three positions [making (9*3) 27 tones all together] and doubles in frequency going to the left . As four notes are repeated in tonation we have only 23 tones in Santur. The Santur is primarily tuned a variety of different diatonic scales which utilizes 1/4 tones or semi-tones. There are 12 modes of Persian classical music which is known as the "Radif" which consists of 12 Dastgahs or Modes. Each Dastgah has its own tuning and character which derives from the different parts of Iran (Persia) which dates back thousands of years and was only preserved thru performance until the late Ostad Abol Hassan Saba the legendary Master of Persian classical music, who notated and categorized 3500 years of Persian music into the "Radif of Saba."