3M High Temperature Flue Tape stops hot air leaks where they start – the seams of your heating ducts. The flue tape is heat resistant up to 600° F. 3M High-Temperature Flue Tape is easily installed around seams in hot air ducts. It stops hot air leaks and may be used on surfaces up to 600 degrees F (315 C). Measures 1-1/2 inch by 15 foot This is a two pack