The Seung is a plucked string instrument with the strings strung up over the sound box. The musical sound is produced by plucking the strings. The number of strings varies according to which part of the country that Seung comes from. This kind of instrument is called the Pin (ปิน) in some localities. However, in some literatures as well as in the folkloric poem “Klong Nirat Hariphunchai”, this instrument is mentioned as the Ting (ติ่ง).
         The sound box is made of a piece of hard wood hollowed out and covered with a circular flat sheet of wood perforated in the center to produce the resonant sound. The long finger board (Tuan) is square-shaped with a flat front side for lining up the strings. The top end of the finger board is grooved and pierced to receive the four tuning pegs, two on the right and two on the left. The strings made of brass wires are attached to the tuning pegs and lined up in two pairs, two strings for the principal pitch and the other two strings for the lower pitch. Using two strings to produce the same pitch is in order to increase the loudness and resonance.
         The sizes of the strings are different. (Two strings are large while the other two are smaller.) These strings are lined up over the wooden bridge (Yong) which supports the strings in the middle of the sound box. There are 9 frets (Nom) made of small pieces of wood fixed at different intervals to obtain different tones of the scale. The topmost fret is widest, while the ninth fret, which is nearest to the sound box, is as wide as half of the finger board (Tuan). The end of the finger board is flat and curved to the front. To play the instrument, it is held against the front part of the body by the left hand which also fingers the frets. The right hand holds the plectrum, which is made of horn or animal bone.
The Seung can be generally categorized into 3 types according to its size.
         1. Seung Luang or the Large Seung: The sound box is about 30 centimeters wide, 6 centimeters thick and 130 centimeters long. This type of Seung produces low sound. It is played in harmony with other types of Seung. The main function of the Large Seung is similar to that of bass guitars in western music.
         2. Seung Glang or the Medium Seung: The sound box is about 25 centimeters wide, 5.5 centimeters thick and 110 centimeters long. Its function is to produce the main melody of the songs. It can be alternately improvised with the Large Seung and the Small Sueng.
         3. Seung Lek or the Small Seung: The sound box is about 20 centimeters wide, 5 centimeters thick and 90 centimeters long. It produces high pitch sound. To make the songs interesting, the musician uses skillful improvisation techniques to make the sound in harmony with the other instruments in the ensemble.
         Apart from being a good solo instrument, the Seung has different functions in different kinds of mixed instrument ensembles, such as the Salaw-Saw-Sueng ensemble, the Pii Jum ensemble, or the Saw Nan ensemble. Practically, the strings of the Seung are tuned in 2 ways.
         - Seung Luk Sam: The low pitch strings are tuned to the low ‘Do’ pitch and the principal pitch strings are tuned to the ‘Sol’ pitch. Usually the Seung Glang or the Medium Seung is tuned in this way.
         - Seung Luk Sii: The low pitch strings are tuned to the ‘Sol’ pitch and the principal pitch strings are tuned to the high ‘Do’ pitch. Usually both the Seung Luang or the Large Seung and the Seung Lek or the Small Seung are tuned in this way.