40 Cubic Foot Inert Gas Cylinder suitable for all inert gases including: Argon(75%)/CO2(25%), Argon or Nitrogen. Argon/CO2 mix provides superior performance while welding with solid steel MIG wires. Straight Argon is suitable for most TIG applications and aluminum MIG welding. Nitrogen is used for various industrial applications including HVAC purging and testing. All cylinders are brand new 3AA2015 with ten year test. Cylinder dimensions: 7.0"OD X 17.5"H. CGA 580 valve.