The Forever Cap Ccsse1313 13 x 13-inch Stainless Steel Single Flue Diamond Mesh Chimney Cap ZVV3A_IB710

Product details:

Will fit flue sizes from: 11-1/2 in. x 11-1/2 in. to 14 in. x 14 in. Hood size is 18" x 18" ; 100% Stainless steel 24-Gauge stainless steel hood and base with build-in screening 8 in.