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. The Snowflake decals are designed to be placed on the OUTSIDE of a window. As a rough guide, we recommend one decal for every 2 feet section of glass. For maximum protection, scientific studies suggest placing decals 2 inches horizontal, by 4 inches vertical, from one another. Reapply decals every 6-9 months.
CONTENTS: 4 Decals per Envelope. TYPE: Static cling.