The US Stove Company COD8 ash clean out door is for use in masonry chimneys and can be used for new construction or to replace an existing door. Making sure that your clean out door is in the best mechanical condition will help to ensure that you can keep your chimney clean and in proper operating condition. It is made of heavy duty cast iron to reduce warping. It comes with the door and frame. The door opening is 8 x 8 in.