Frost King Ventilators with Screens, 10" High, Fits 21 -37" Wide The original W.B. Marvin screens are hassle free - install without tools Plated easy-gliding steel rails for fingertip adjustment Varnished wood ends and coated steel screening Expands easily to fit your window Louvered panels let fresh, healthy air in - keeps rain, snow and wind out 10-Inch X 21-Inch - 37-Inch Louver Metal Rail Extension Window Screen Extends From 21-Inch To 37-Inch Painted Metal Rails, And Varnished Wood Ends Extra Sturdy, Tenoned Corners That Keep Screens Square Comes With Zinc-plated Nails