This foil balloon is suitable to inflate with air. / This balloons is self sealing so no tying with fingers required. / Uses MicroSeal technology for strong and longer lasting seal with a seamless appearance / 0 to 9 numbers are avaliable, Select the Letter you want to buy. / Blow them up with either your mouth, air balloon pump. Foil Balloon Does not Float with Helium / Great for small and large events decoration. Use them for parties, birthdays, weddings, holidays, and special occasions.