4 ft / 48 Inch Giant Jumbo Round Latex Balloon (Premium Quality), Pack of 1, Blue The opening of the balloon is 8 cm wide. Fully inflated, this balloon contains 1 cubic meter of air or Helium corresponding to 1000 liters. Tensile strength if filled with helium, is 2000 gram. It is best to inflate this balloon with an electric balloon pump. The balloon can best be closed with an 15 cm clip. Shipped uninflated. Can be air filled or helium filled