**Principle Of Operation：the rings of this chimney cowl are specially designed and placed over the other in a way that the wind cannot go down the chinmey, thus making this cap a prefect anti downdraught solution.enough to prevent rainwater from entering the ventilation system. **Stainless Steel Rotating Chimney Cowl Cap: Spinner Anti-Downdraught Fits Most Standard Chimney Pots Very effective in preventing wind and increasing ventilation.Rotating hood for ventilation pipes, chimneys, and air extraction.The gairing provides maximum protection without hindering the performance of the chimney. **Wide range of application: widely used in large-scale factories, warehouses, stadiums, livestock farms, high-rise buildings, residential buildings, etc., to effectively indoor oily , , peculiar smell, moisture, heat, and decoration Harmful gas and dust etc，Can be installed directly without complicated assembly； **Protect your chimney from rain and moisture, which is especially suitable for chimneys that are not used frequently.Stainless steel construction Thickened fixed feet; Spinner Anti-Downdraught Fits Most Standard Chimney Pots Very effective in preventing wind and increasing ventilation. If you have any questions, please do not hesitate to contact us. Thank you for coming, wish you a happy life！