This fun multicolored rainbow polka dot and striped square Happy Birthday mylar balloon is a fun way to say your care. Mylar balloons are such a fun and unique way to liven up a party. Our mylar balloons come uninflated. You can take them to any party store and have them inflated with helium or hi-float. All our mylars vary in size and go great with any of our latex line. Measures 18 inches across.