Aspen Leaf pack of 8 leaf decals. Window Alert decals help prevent wild birds from accidentally striking windows. Each decal has a special coating that reflects ultraviolet sunlight. This ultraviolet light is invisible to humans, but birds see it as a brilliant glow much like a stoplight. To the human eye, the decals appear as frosted or etched glass. The decals measure approximately 4 inch across and are designed to be placed on the OUTSIDE of a window. As a rough guide, we recommend one decal for every 3 ft x 3 ft section of glass.
UV coating may fade based on exposure and local elevation. Replace decals every 9 to 12 months.