WindowAlert WINDA3 Butterfly Decal, 4 in L, 4 in W

WindowAlert 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. Butterfly decals measure approximately 4 in across. WindowAlert decals are designed to be placed on the outside of a window. As a rough guide, we recommend one decal for every 3 x 3 ft section of glass. For best results, replace decals every 4 months or test with the WindowAlert UV flashlight.