Air Tank: An air tank (more commonly called a “scuba tank”) is a metal container that safely holds the compressed air we breathe underwater. Modern scuba tanks are made from aluminum or steel and can to hold air pressures as high as 3500 psi (That is 100x the air pressure in your car tires!). Our SCUBA Regulator attaches to the air tank valve. When our air tank empty it is refilled with a special air pump, called an air compressor. Required Features Valve: The valve controls the flow of air from the air tank by simply turning the knob open or closed. Burst Disk: Part of the valve, the burst disk is a safety device that releases the air from the air tank if the air pressure gets dangerously high. Inspection Decal: For safety, air tanks must be inspected annually. The Inspection Decal shows dive shop employees filling it that it is within the inspection cycle and may be filled. Nose Pocket: This HP Steel 3.5 Air Tanks Mr. and Mrs. Brown use High Pressure Steel Air Tanks. HP Steel tanks are heavier and more compact than air tanks made from aluminum. Mr. Brown uses 100 cubic foot air tanks. Mrs. Brown prefers smaller, shorter 80 cu.ft. air tanks. Special HP Steel 3.5 Air Tanks Features Steel: Steel is stronger than aluminum so air tanks can be made more compact and hold more air than aluminum air tanks. Galvanized Steel: The outside of the steel tank is "galvanized" (specially coated with zinc) to prevent the steel from rusting in salt water. Heavier Tanks: HP Steel Air Tanks are heavier than aluminum air tanks. This is actually a good thing for diving underwater because when we dive the extra weight is spread out over a larger area and we can wear less weights in our Integrated Weight BC. High Pressue: HP Steel 3.5 Air Tanks hold air at a higher pressure (3,500 psi) than aluminum air tanks, so HP Steel Tanks can hold more air. That means we have more air to stay longer underwater. HP Valve: HP tanks require the use of special high pressure DIN valves. We have changed the air tank connectors on our regulators to DIN valve connectors.