cannot decode most of the stamped letterings.
what is important would be 2005/5. this is the date (month) when your cylinder was hydrostatic tested. there is a requirement where co2 cylinders need to be hydrostatic tested every 5 years. the test date is stamped on the neck of the cylinder.
when you were sold the cylinder, what were you told regarding the size? 3.5 litres?
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