The XS Scuba Metal Impact Aluminum SCUBA tanks are durable, reliable, and visually appealing. The tank is manufactured from the industry standard lightweight, high-strength aluminum 6061-T6 alloy. The 40 cubic foot tank is an ideal volume cylinder for use as a large capacity pony bottle, redundant air supply system, bailout or moderate duration decompression/safety stop gas supply. A pony bottle is a smaller tank, which is carried in addition to the main tank. It possesses its own regulator with first and second stage and sometimes a separate pressure gauge. It is mounted either at ones side or in front of the body or fixed to the main tank. A pony bottle scuba tank is the only true redundant breathing mechanism you can completely rely on. The 40 cubic foot cylinder is also an excellent choice as a primary cylinder for young divers. The 40 cubic foot pony bottle has a 3000 psi (207 bar) service pressure rating, a capacity of 38.8 cu. ft. (5.5 liters), is negative 1 lbs. (0.5 kg) when full and is positive 1.4 lbs. (0.6 kg) at 500 psi (35 bars). Cylinder weighs 15.3 lbs. (6.9 kg) when empty, and measures (Dia. x L) 5.25" x 24.9" (133mm x 633mm). Aluminum cylinders unlike steel cylinders dont rust, they oxidize. The oxidization of aluminum forms a protective coat that hinders the continuation of corrosion making aluminum cylinders less likely to be condemned due to excessive corrosion. When shipped the tanks valves will be removed and the tank will require re-inspe