Perfect Sunburst: Patent pending design. Wood blind slats are used as louvers that are fully adjustable and spring tensioned to allow slats to be set in the open or closed position. Installer positions slats initially, thereafter; slats can be adjusted after installation one at a time. When fully closed, arch darkens the room like a blind. Exclusive light stops soften the light at both ends of the slats. Adjustable valance hides the mounting screws and lets you align the arch with nearby windows. See chart to determine which size perfect arch to order.