The Top Damper seals out rain, snow, and sleet while sealing in "paid heat and air conditioning. In its closed position, it is virtually invisible from the ground. The stainless steel and cast-aluminum design ensures that it won't rust or stain your chimney. The Top Damper doesn't require a chimney fire safety device, cutting costs and saving time! The Top Damper's unique lid is made of cast-aluminum which reduces its weight, allowing the damper to open higher and close easier, as well as decrease stress on the springs.