This cap is fitted between two 24 gauge, 304 stainless steel sheets to reduce heat loss. The cap is sealed tightly to a high temperature silicone and gasket, both able to withstand temperatures from 85 to 450 degrees F. The Damper is constructed of 304 stainless steel, offers a 3/4 expanded mesh screen and features a removable lid, making it easy to clean. Its lid is also 15% larger than most, offering greater protection from the elements and reducing the amount of snow buildup and ice. Specifications. Size 13 x 13 in.