Aluminum foil "HAPPY BIRTHDAY" balloon set. The package comes with the string/ribbon and a straw. All letters are blown separately with the air from mouth. They can be filled with helium but it is preferred to fill air by mouth. Warm Tip 1: Helium filled balloons would not float upright. Warm Tip 2: In case the reseal valve does not seal properly, you may use a small piece of transparent tape to seal the valve