Features: 1) Chimney pipe length: 3', 6', 9', 12', 18', 24', 36' 2) I.D.: 4' - 24' 3) Material: 304 Features: 1) Chimney pipe length: 3', 6', 9', 12', 18', 24', 36'2) I.D.: 4' - 24'3) Material: 304 stainless steel inner and 430 stainless steel outer4) Non insulated chimney pipe with 1" thick wall packed with air