WindowAlert Hawk UV Decal helps prevent wild birds from accidentally flying into your windows by making glass surfaces visible to them. Each decal features a special coating that reflects ultraviolet sunlight, which is invisible to humans but appears as a bright glow to birds, similar to a stoplight. To effectively use the decals, simply place them on the outside of your windows, concentrating them at the center and then working outward. It is to position decals at least every 2 feet across the glass. For optimal protection, scientific studies suggest spacing the decals 2 inches horizontally and 4 inches vertically from each other. This easy-to-apply solution helps protect birds while maintaining an unobtrusive look for your home. Model Number: