Quite thick aluminum tape with good adhesive during application BUT after at least 10 ignitions of the stove it smells, and it smells a lot to the point that if you want to raise the fire in the stove the whole room stinks. It has been installed on the wood stove's flue about a meter higher than the soup outlet. Another aluminum tape, not painted, silver from a Greek company, didn't smell at all on the first ignition. At the first opportunity, it will be removed and replaced.