The composition of the hose is similar to the articulated part of a straw. It is made of relatively thin material, which is layered in several pleats similar to an accordion. This results in a high flexibility of the tube. This is advantageous when diving, because even with strong bending, the diameter remains big enough that sufficient air can flow through it.
The hose is not recommendable for a snorkel. Because water can accumulate in the pleats, which you cannot properly clear.
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