Have the most memorable party with your friends and family by decorating with this balloon featuring a Happy Birthday headline surrounded by colourful stars, planets, and rockets. This balloon will add a warm atmosphere to your party. 1 round foil balloon that measures 18. This balloon features a Happy Birthday headline surrounded by colourful stars, planets, and rockets. This balloon will make your party more fun and unforgettable. This balloon is made of durable foil. You can fill this balloon with helium to make it float.