These balloons have an automatic sealing valve. They can be filled with air so they can be fixed to the wall or can be filled with helium so that they float. These balloons will make a great decoration for your children's party. Or buy as a surprise gift for any occasion! Please note that these balloons will come flat and not inflated, you must inflate these balloons yourself. The Sonic character balloon measures aproximatley 29" and the tails character balloon meausres aproximatley 33".