"I ordered 10 of these balloons for my twins first birthday party. They were adorable and we got lots of compliments on them. I took them to a local party store to have them filled with helium (at a cost of .59/balloon). One of the balloons would not inflate and the store even refunded me my .59. The other nine balloons did well. Since these were mylar balloons (not latex), I expected that they would stay inflated for a while. Only one of them still looked completely full after a couple of days. The others still floated but were looking a bit ragged. This was disappointing to me because my in-laws hosted a second party for the twins a week after the first party. We were able to "recycle" several of the balloons but they weren't as full or "plump" as I would have hoped."