Millions of wild birds are killed each year flying into windows. Now you can help reduce this loss of life. * WindowAlert is a low-tack decal that may be applied to home and office windows. The decal contains a component which brilliantly reflects ultraviolet sunlight. This ultraviolet light is invisible to humans but glows like a stoplight for birds. Birds have vision that is up to 12 times better than that of humans. * WindowAlert decals help birds see windows and thus avoid striking the glass. 3 foot long roll of clear shapes for the humming birds to see.