The DuraVent 12DCA-CTC is a chase top collar from the DuraChimney II collection, an air-cooled chimney system that is designed for use with masonry fireplaces. With an inner diameter of 12 inches, this is used to construct custom-sized chase tops. This is also used to provide necessary ventilation and spacing for the chimney system. A limited lifetime warranty is also being offered by DuraVent when purchased.Recognized as a technological leader in the venting industry, DuraVent is committed to provide quality and innovative products for their customers. Discover their products here at PlumbersStock.com.