Fire Damper; Item Damper; Type Rectangular; Overall Size 24 Inch Width x 18 Inch Height; Material 22 Gauge Steel (Frame/Blade); Finish Galvanized; Mounting Type Horizontal; Material Negator Stainless Steel (Closure Spring); Fire Rating 1-1/2 Hour; Fusible Link 165 Deg F; Approval UL (Canada and US), UL 555