These chimney caps are designed as replacements for "Air Insulated" factory built chimneys or prefab fireplace stacks with the listed size as the inner diameter. The outer diameter is 17" and uses a special construction to maintain proper internal venting on double or triple wall chimneys. These use a friction fit collar for universal application and easy installation and cleaning.
304 - Alloy
Replacement for most manufacturers air cooled chimneys
Friction fit fits 99% of chimneys with the proper inner diameter