Fenestrelle expanding window screens feature a strong, white, powder coated aluminum box frame and fiberglass fabric screen that will hold up to the harshest of conditions. Weather stripping top and bottom adjusts to rough surfaces and keep small critters from sneaking in. Our adjustable design allows you to change the window from a horizontal sliding orientation to a vertical sliding orientation. Just open you're the lower pane of your single or double hung window; expand the Fenestrelle screen to fit; and drop the sash to hold the screen in place. Keep mosquitoes, flies, wasps and other flying pests out Standard orientation horizontal: minimum 15 in. high x 21 in. wide, expands to 40 in. wide 90 orientation vertical: convert to minimum 21 in. high x 15 in. wide, expands to 28 in. wide (minor disassembly required) Perfect for older windows