The small muffled flute, commonly known as the leather whistle, is a double-reed gas-sounding instrument of the Yi nationality. In Yi language, it is called Yahalu or Benmaihei. In Yi language, "Benmaihei" means insect shell, and "Dili" means flute, which means the flute whose shell is used as a reed whistle.

The traditional folk flute consists of a pipe body and a pipe whistle. The tube body is made of bamboo, generally made of phoenix-tailed bamboo or bitter bamboo shoots with the thickness of the pen tube grown locally, and also made of reeds or winged quills.

The tube body is transparent from top to bottom, the tube length is 7 cm to 15 cm, and the inner diameter of the lower opening is 0.7 to 0.9 cm. There are three, four or seven circular sound-pressing holes on the body of the tube, all of which have a back hole.

The most popular four-hole small muffled flute is commonly made of thin bamboo pipes with a tube length of 7 cm and an inner diameter of 0.7 cm. The three sound holes are opened on the front, and the hole spacing is 1 cm. between the holes. A double-reed whistle is inserted into the top of the tube. The pipe whistle is made of worm cocoons, the shape is snake head, and the whistle is 1.5 cm long. and other processes.