Dragon Rotovent Chimney CowlRotowent Dragon Chimney Cowl Powder Black The Rotowent Dragon chimney cowl is a device that dynamically uses the force of the wind to increase chimney draught and prevent downdraught. The cap always places itself in the opposite direction to the wind, no matter its strength or direction. It can be mounted on gravitation based chimney ducts, ventilation, flue and smoke. The special patented rotating system has ball bearings, which are uniquely placed