These are Made of high quality aluminum foil, thick and auto-sealing, no leaks, can last for days when inflated. Give Your Big Party A Personalized Presentation With Foil Balloons! This Collection Of foil Balloons Features "1st Birthday Boy & Girl Foil Balloon set, So You Can Mix And Match. Whether You'Re Celebrating A Birthday party, These Shining Baby Boy & Baby Girl foil Balloons Are Perfect For Your Celebration. Mix And Match With Coordinating Foil And Latex Balloons, Polka dot balloons & balloon accessories