TECHNICAL SPECIFICATIONSITEM 1: 700 BALLO?NS 350 gr The balloons will be inflated with hydrogen and will be used to carry meteorological equipment into the upper atmosphere. ?he balloons should be free from foreign matter, pin-holes or other defects and must be homogeneous and of uniform thickness. Also they must be spherical or slightly pearshaped when inflated and shall be capable of carrying a load of at least 500 gr at a minimum rate of ascent of 300 m/min to an altitude of 24 km or more. The necks shall be pliable enough to be easily sealed with a knotted string yet strong enough to support a weight of 500 gr without damage to the rubber. The necks of the balloons shall be at least 100 mm long when the balloons are inflated, and the internal diameter of the neck shall be 30 - 45 mm.shall be made from natural or synthetic, rubber latex.ITEM 2: 3000 BALLO?NS 30 gr For optical wind measurements in the upper layers of the atmosphere made of high quality, suitably compounded and elaborated, extensible rubber latex being homogeneous and of uniform thickness, free from foreign matter, pinhole or other defects. The balloons shall be capable of inflation, with air at ground level to the full minimum burst test diameter without bursting or developing pin holes. When securely closed at the neck they shall retain this diameter and spherical shape for at least an hour. The neck shall be strong and shall be not less than 8 cm in length when the balloons are inflated. They shall be of suitable thickness which will allow a knot to be tied without difficulty when sealing the inflated balloon. The internal neck diameter should be 17� mm, the minimum burst test diameter 72 cm, rate of ascent 150 m/min, bursting altitude at least 8 km and the colour red. The balloons will be inflated with hydrogen or helium. shall be made from natural