Blue Sparkle Happy 21st Birthday Foil Balloon This bright Happy 21st Birthday Balloon makes the perfect accessory for a boy's 21st birthday party. This fun 18” (45.7cm) holographic foil balloon comes flat packed and comes with a length of ribbon to make it even more fancy. Helium isn't included, but you can either fill woth conventional air or purchase helium from party shops. Round blue 'HAPPY 21ST BIRTHDAY' balloon. Holographic foil (both sides show the same design). 18" (45.7cm). Flat packed & includes a length of ribbon. For best results fill with helium (not supplied) or fill with air. Manufacturer's Warning: Not suitable for kids under 3yrs when balloon is attached to a ribbon - entanglement/strangling risk.