Our Class ''A'' cap is a great alternative for a Class ''A'' Chimney System with solid pack insulation. The ACS Class ''A'' is made of 24 gauge 304 stainless steel. It is designed for lifetime use with a removable lid for future cleanings. Features: Material: 304 Stainless Steel. Class ''A'' Cap. Specifications: Overall Dimensions: 15'' (L) x 15'' (W) . Note: We do not accept buyer's remorse returns on these products. Please make sure it works for your needs before ordering. Stainless Steel & Copper chimney caps have a Lifetime Warranty.