Chim-A-Lator Deluxe Top Sealing Damper Stainless Steel 12" x 12" (part# 051212) 100% Stainless Steel - Lifetime limited warranty is best on the market today. Comes fully assembled for fast and easy bolt on installation. Spark arrestor standard. Chimney fire tested with little or no damage to unit damper. Will not fall and block flue in event of a chimney fire. Saves energy. Tight seal on top of the chimney, keeps heat in when fireplace is not in use. Prevents down draft smoking caused by wind. Keeps out animals, birds, insects, bees, rain, leaves, wind and airplane noises. Six setting regulator controls the amount of draft to produce mored heat when burning. Damper opens 6.5 inches.