Every year, many birds die by flying into the windows of buildings. To prevent this easily, bird silhouettes can be attached to window panes as a warning for the birds. The bird can perceive the window or glass door as a dangerous area and will not fly into the otherwise invisible pane. This effectively and simply prevents injuries and fatalities. The set includes three designs in different sizes. The stickers are made from high-quality foil that is resistant to UV rays and can be used outdoors year-round.