The Khen (also Khaen, Kaen, Khene, Caen) - a bamboo harmonica!
The origin of this instrument is Laos, but it is also made in Thailand and in Vietnam. The mouthpiece of the Khen is approximately as large as a normal harmonica. The Khen itself is approximately one meter long. So it is not an instrument which you can carry with you in everyday's life. Its sound can't be appreciated every day, either!
The Sheng is played like a recorder but with two hands simultaneously. Blowing and drawing in the air can produce different tones, which is typical of a harmonica. The sound is generated by very thin metal tongues (bronze, copper or brass alloy) in the mouthpiece. The pitch depends on the natural frequency of the metal tongues, the whistles length, and on (usually) two cuts at the back of the whistles (bamboo canes) as well.
In contrast to the cognate Chinese Sheng or the Japanese Sho, where the whistles are arranged circularly, the Khen has only two simple rows of whistles.