These stickers help birds recognize glass, reducing collisions. They can also be attached to glass doors to warn people and pets, preventing them from bumping into the door. These decals are made of prism window film, catching sunlight to create rainbows in your room. They are suitable for both indoor and outdoor use. Simply peel off the backing and stick to the glass using water; no glue is required. They are removable and reusable. You will receive 15 bird stickers in 5 different styles, with 3 pieces of each style. The decals range in size from approximately 11cm to 20cm.