Crazy Helium Display 12-piece Helium Canister is designed for filling balloons. One canister can approximately fill: 10 5-inch latex balloons, 4 10-inch latex balloons (partially inflated), 3 12-inch latex balloons (partially inflated), and one 19-inch foil balloon. Many factors influence the degree of inflation and the number of filled balloons, including the balloon manufacturer and weather conditions. The 10 and 12-inch balloons must be partially filled with helium. When you feel them starting to rise, inflate them to their full size. The container is under pressure: protect it from sunlight and heat above 50 °C. Avoid extreme weather conditions and keep away from ovens, fireplaces, or open flames. Do not puncture or burn even after use. Keep out of reach of children. The can contains Hel gas. The gas is neither harmful to health nor the environment. Helium is gaseous and may therefore look like an empty can. The seal on the lid guarantees full capacity. A broken seal does not guarantee 100 percent content.