Help prevent birds from flying into windows, doors and greenhouses which can cause injury or death. Translucent decals reflect ultraviolet light so they appear like frosted glass to humans but show clearly to birds. Reusable self-adhering decals remove easily. Each pack contains four different decals approximately 4" across. Snowflake design. WindowAlert decals may be used only on an EXTERIOR glass surface -- free of any overlay, tinting, film, or coating. Clean glass thoroughly. Make sure glass is free of chemicals and cleaners before applying decals. Decals are best applied when glass is warm (greater than 50 degrees Fahrenheit). If applied during winter months, clean glass with warm water prior to application. Peel decal from paper backing. The same side that was against the paper goes the against the glass. Place decals on the outside of the window. Concentrate decals at center then work out, placing decals at a minimum, on every 2 feet of glass. For maximum protection, scientific studies suggest placing decals 2 inches horizontal, by 4 inches vertical, from one another. UV coating will fade based on exposure and local elevation. For best results, replace decals every 4 months or test with the WindowAlert UV Flashlight. Position out of reach of infants and small children. Restore static cling by rinsing in lukewarm water.