Single-layer adjustable shutter air port is often used in the pipeline for suction, conveying air, and can also be fitted with a man's gate (multi-leaf paired regulating valve) according to the actual situation, for controlling the air volume or installing an aluminum alloy filter, for supporting use. A lëu bɛ̈n ya tɔ̈ɔ̈u ka tɔ̈ɔ̈u ka tɔ̈ɔ̈u ka tɔ̈ɔ̈u ka tɔ̈ɔ̈u ka tɔ̈ɔ̈u ka tɔ̈ɔ̈u ka tɔ̈ɔ̈u ka tɔ̈ɔ