Military surplus weather balloon made by Kaysam. Balloon can be inflated over 12 feet diameter and is in sealed plastic bag. Bonus feature of this offering is that a canister of Calcium Hydride is included to inflate the balloon. This is a very hard to find item. T are perforations on the top of the can to puncture. Water is added to the can and it is inserted into the neck of the balloon to inflate it with hydrogen gas. You must be careful because hydrogen is an explosive gas that can be ignited by a spark. These items are sold as is without liability on my part and not for sale to anyone under 18 years of age. I may request the buyer to e-mail me a copy of their driver's license to prove age-you may blank out license number but I need name and birth date. I have inflated over 50 of these balloons during my time in the Army and it is safe to do if you are careful.