Cast Aluminum and Stainless Steel Construction. Lifetime Warranty. Reduce heat and air conditioning loss by 90%. Mount easily atop tile with silicone sealant included; 32' stainless steel cable also included drops down the flue and mounts to firebox wall. Spring action for easy opening. Fire safety device locks the damper open in the cast of a chimney fire. Available in six sizes. Featured on This Old House home improvement show.