Weather-resistant metal louver panels shed rain, snow, and sleet. Lets draft-free air in while keeping out flying bugs. Fingertip adjustment to fit all sash windows. Coated metal screen resists tears, weather, and bugs. Durable construction painted metal rails and varnished wood ends. Install adjustable screen window ventilator from inside. 10" high. Adjustable from 21" wide to 37" wide.