Spherical dewar-type tank made of Inconel (nickel-steel alloy). Outer diameter 26.55 inches and wall thickness is 0.020 inch. Tanks with accessories are 36.39 inches tall. Tank has an inner vessel with a diameter of 25.06 inches and wall thickness of 0.061 inch. Rupture pressure of the tanks is 1530 pounds per square inch. Insulation between the inner and outer shells is fiberglass, paper mating, and aluminum foil. Tank weighs 791/2 pounds, has a volume of 4.73 cubic feet, and a capacity of 320 pounds - 210 pounds for fuel cells and 110 pounds for environmental control.