Now you can protect wild birds from windows. Millions of wild birds are killed each year flying into windows. Now you can save the lives of the beautiful birds you love. WindowAlert is a static-cling decal that may be applied to home and office windows. The decals contain a component which brilliantly reflects ultraviolet sunlight. This ultraviolet light is invisible to humans, but glows like a stoplight for birds. Includes four 4" hummingbird decals. Made in the U.S.A.