LOONBALLOON Birthday General Balloons, 18 inch THANK YOU DAD FOR EVERYTHING! Accent your Father’s Day or Dad’s birthday themed party with this 18in. round Thank You Dad For Everything! foil mylar balloon. The perfect balloon for your Father’s Day or Dad’s birthday party, this 18in. 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.