bond length that it is possible to freely adjust the indoor air and outdoor air that is mixed to prevent so , the large diameter of the tubular body and the outer surface of the insert is formed by a small diameter size of the small-diameter portion and the large diameter portion made of the inner surface , installation inside the body in the longitudinal direction on the inner surface of the body is divided into two , and the large-diameter readily available and that the connector of the ventilator construction is easily made for adjusting the length according to the connection portion provided in the small diameter portion and that the wall thickness of the building blocks , including a plate-like body formed in a shape that is inserted into each combination provided .
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