It was a simple wind instrument, forerunner of the flute. It consisted of one long bone, cane, or metal tube, open or closed at one end, with one or more finger-holes. It did not have a reed and the player held it sideways on his lips to the left, and blew directly into its open end.
There was also a variation of this instrument where the blowing was executed from a special hole on the side (“plagiaulos”).