Quantity: 1 Bring your Transformers party to life with this 18 inch round Transformers Optimus Prime foil mylar balloon! This Party Brands balloon features Optimus Prime and is perfect for using in a Transformers themed balloon bouquet. Pair with some of our other Transformers foil mylar and latex balloons for a great design! This balloon includes a self-sealing valve preventing the gas from escaping after it s inflated. The balloon can be inflated with helium to float or with a balloon air inflator. Balloon arrives uninflated.