Frost King Aws1837 Metal Rail Extension Window Screen, 18" X 21" - 37" 18" high, fits 21" - 37" wide This is the original, high quality "W.B. Marvin" screen Plated easy-gliding steel rails for fingertip adjustment, wood ends and coated Aluminum screening Bright mesh screen wire, extends from 21" - 37" Galvanized rails and varnished wood ends