Reusable 18" Happy Birthday Party Foil Balloon Self Inflating Air Baloon Unicorn

How to use: Gently push the supplied straw in through the valve, blow the balloons up through straw, once the balloon is up, remove the straw, all done. How to deflate and reuse: push a standard drinking straw (not supplied) through the valve, until air is released (about 10cm deep in).

eBay