This is an aluminum 22 cubic foot nitrogen tank with a CGA 580 valve. It is most commonly used to serve nitrogen or beverage gas when pouring stouts in your draft system.
These tanks are sold empty and will need to be filled by a local gas supply company
Typically new tanks are good for 5 years before you have to retest them (hydro test). I currently have three that were due for hydro testing in 2021. These are marked down by $80 to move them out. The other one I have is due in June 2023, this one is marked down by $60 to clear it out. Both are a great deal!