These are Made of high quality aluminum foil, about 16 inch 0 to 100 Number Digit and 16 Inch Happy Birthday Alpabets, 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 Metallic Balloons Features Every Alphabets From A to Z and Numbers, So You Can Mix And Match To Form Any Number Or Happy Birthday Letters. Whether You'Re Celebrating A Big Birthday, These Shining Happy Birthday Rose Gold foil Balloons Are Perfect For Your Celebration. Mix And Match With Coordinating Foil And Latex Balloons accessories16" Inches Happy Birthday Balloon X 13 Alphabets16" Inches Number Balloon X 1For all occasions including birthday, anniversary, mothers day, valentines day, shower party, new year, kids birthday, Christmas partyBirthday Occassions For Kids, Girls, Babies, Infants, Boys, Mom, Dad, Brother, Sister, Husband, Wife, as well as Boyfriend & Girlfriend Surprise Birthday PartyThese are self-sealing balloons. Tying with fingers is not needed. It has Self-sealing and is reusable. The foil balloons automatically seal when you stop filling them ?Tying, twisting, or Putting a knot is not necessary.?hoto friendly. Numbers and Letter balloons simply can be used as props or to decorate your wall with them.