What capacity CO2 cylinder have I got?

[sonicated]

There was a mix up about a year ago when I got my CO2 cylinder and I got the wrong size. I want to work out when it's getting empty to arrange a refill but I don't know what weight it will go down to.

Freshly delivered it weighed 14.5KG. It's about 7 inches wide and 24 inches tall. I was offered 3, 6 or 9KG of CO2 but the guy on the phone last year couldn't tell me which one I have. Can you help?

Here it is next to a corny:

[phil.dadd]

Should have the weight of the cylinder stamped into it?

[sonicated]

There's markings but nothing legible. I think one part says 35 KG, but that's obviously not right. If it's 15KG which is close to what I weighed it as it still doesn't tell me the CO2 capacity.

[sonicated]

On closer inspection I think it says "6 . 35 KG"! Thanks for your help