HomeSaver 7″ Pro Cap for Solid Pack Factory-Built Chimney Solid Pack Tight, friction-fit installation allows this cap to slip down securely inside the chimney. It fits virtually any brand of factory-built chimney. Some brands will, however, differ in their inner dimensions by a few fractions of an inch. The top and bottom of the solid pack cap is 13″ in diameter. for the Air-Insulated Cap, the 16″ diameter, along with special construction for proper internal venting, allow it to work for either double or triple-wall air-insulated chimneys. Features: Material: 304-alloy stainless steel. Lifetime Warranty. Replacement cap for factory-built chimneys. Friction fits any brand of chimney. Specifications: Overall Dimensions: 13″ (W). Round Flue Size : 7″. 1″ square mesh, 4″ high.