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 two that are due for hydro testing (2021). The ones due are marked down by $80 to move them out. The other three are due in June 2023, these are marked down by $60 to clear them out. Both are a great deal!