Secure Temp’s 304 .016" thick inner wall resists oil and coal corrosion better than the less expensive 430 stainless. The outer wall is .016" thick 430 stainless. Couplers are .014" thick and are made of 430 stainless steel.
The floating flue, first designed by Security Chimneys, along with the double overlapped seam allows them to warranty their chimneys against chimney fires and corrosion, as well as workmanship and materials. Secure Temp has a 2" clearance to combustibles.