16" Happy Birthday Alphabet Foil Balloons Banner, Balloon Type and Size: Microfoil Size of each balloon: approx. 16inch (41cm) tall Air Filled Normal (Balloons cannot float); • Balloons will stay inflated for approximately one week (not floating) • String come with the balloons up by hand upon receiving Float Time: • Balloon will stay inflated for approximately one week (not floating) Cold air, hot air, high humidity, changing barometric pressure, high altitudes, and moving air from fans and vents will reduce balloon float times. The float times posted on our site are the maximum to be expected. Changing conditions mean that on some occasions balloons may float for only one day and on other occasions the same balloons may float for many days. We guarantee that your balloons will be delivered in perfect condition, but float times will vary. There are no guarantees for float time if balloons are displayed outdoors.