These super colourful medium size 41cm Northstar Number 9 foil mylar letter balloons are best way to celebrate a milestone birthday! These massive balloons are great for bouquets, photo backdrops, on the top of balloon columns, design them into the top of balloon arches and more. Add colour coordinating mylars and latex balloons for the ultimate balloon bouquet! Inflate these balloons with air only. Helium is not suitable. This balloon includes a self-sealing valve, preventing the gas from escaping after it's inflated. Balloon arrives uninflated.