An air ring has a main body including a plenum through which pressurized air enters the air ring, the main body including a generally circular interior that is unobstructed vertically above the main body. A generally circular forming-cone assembly is received in the generally circular interior of the main body, and includes at least one annular lip defining a passage through which pressurized air from the plenum exits the air ring for impingement upon the polymer tube. A plurality of fasteners secure the forming-cone assembly in the interior of the main body, the fasteners and forming-cone assembly being unobstructed vertically above the air ring, wherein the fasteners are accessible from vertically above the air ring and the forming-cone assembly is removable from the main body by vertical lifting without removal of other components from the air ring.