Quantity: 1 Accent your birthday contruction themed party with this 18 round Construction Party Zone foil mylar balloon. The perfect balloon for your birthday contruction party this 18 Unique party balloon is great for setting the scene! 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.