High temperature resistant 310S stainless steel, 0.025” thick. Unlike common 304 stainless which starts oxidizing at 800F, 310S will not oxidize until 2000F. Burner liner made from this material will not crumble away with continued use. Available only in 4-foot lengths, 6 inches wide. Two pieces are required to line most burners with the usual 2+ inches of overlap.