The Pen-pipe is a musical instrument of the wind family with the free vibrated reed, popular among almost all of Vietnam's ethnicity in different forms.

This musical instrument is called Khen by The Kinh (Viet) group, while the Mong ethnic minority call it the Kenh, and the Ede in the Central Highlands use a similar instrument called Dinh Nam, etc.

The Pen-pipe may have an evennumber of 6, 8, 10, 12 and 14 sections of small hornless bamboo pipes arranged in two rows. Each pipe is fitted with a reed made of a thin strip of copper. The section of the pipes with the reed lies inside the wooden air-chamber. The part of the pipe lying outside it shows a finger-hole. The pipe into which the player blows lies at right angles with the pipes with finger holes.

The pitch of The Pen-pipe's sounds depends on the the length of each section. The sound of The Pen-pipe is not very clear but quite strong, nonetheless; the deepestnotes are rather dull. Special melodies for The Pen-pipe among ethnicity are composed in the style of homophony.

The Pen-pipe is a musical instrument for men and is used mainly to accompany singing. The H'Mong minority group play The Pen-pipe on various occasions, including funeralswhere it is accompanied by drums. When The Pen-pipe is played by one person, the soloist accompanies the music with dancing in which much vigorous knee-bending, body-turning, kicking, etc., is performed.