Vietnamese dan bau or ‘gourd string instruments’. They consist of a trapezoidal sound box with a single string, stretched lengthwise along the body of the soundboard, and a movable bridge with a wooden handle or tremolo bar with half of a dried gourd, attached to one end of the sound box, opposite of the tuning peg. The gourd covers the handle at the very point where the string is attached and contributes to the amplification of the sound volume of the instrument.

Originally, its was made up from the top half of a bottle gourd, though nowadays, the gourd is usually replaced with a more durable turned, wooden, bell-shaped cup. The Vietnamese word bau (bầu) means ‘gourd’, hence the instrument's name.

The Dan Bau is usually tuned to the note C and is played by plucking the string, whilst touching it lightly with the side of the hand. By moving the tremolo bar, the tension of the string can be varied, causing the pitch to rise or fall. In the same way, a note may be lengthened or shortened and subtle glissandi sounds can be produced by plucking the string, whilst pulling the whammy bar.