Party Transformers - Optimus Prime & Bumblebee - Square, Self-Sealing Foil Balloon - 43cm. Balloons delivered uninflated. Helium inflation for flotation available in store only. Autobots, roll out with our Transformers Balloon! This square balloon features Optimus Prime on one side and Bumblebee on the other. With cool metallic detail, it's an awesome addition to your little hero's celebration!