Balloon measures 18 inches and contains 2 units and can be filled with helium or air;please note if you find foil balloons in wrinkle condition due to tight packing/shipping don't worry once the fill with air completely no wrinkle would be visible. After 5-7 days if you think air Presure is little low please fill with more air and enjoy using it. Do not worried about the thickness of the balloons it is made with very ;can be repeated use convenient inflation and deflation. Use a medium width drinking straw and insert it into the self-sealing valve of the balloo then start to blow it. ;shape: hert. Material: foil;material: foil. Uses microseal technology for strong and longer lasting seal with a seamless appearance