Snail fans are ventilation units where square-section and circular air ducts are connected to each other with the material used for blowing fresh air in the air duct or evacuating the air inside. There are a variety of such fans and they all have a separate function. The flow rate and pressure ranges they provide are decisive in classification. Usable environments also vary according to the suction and blowing power. It is manufactured and diversified as dense and rare wings.