It's imperative that the cylinder remains unharmed.
The green colour makes me think it's a halon fire extinguisher.

The cylinder must remain unharmed
It is imperative.
Please do not bully the cylinder.
Given the originally red colour, the slender shape and the mounting, it was probably a gas bottle for acetylene. The valve is missing. The text mentions "Duisburg", probably the location of the manufacturer.
EDIT: Acetylene bottles have thead for a protective cap. So my next guess is a fire extinguisher.
Acetylene and then you jump to fire extinguisher.
I hope I‘m not near you when you try to fight a fire.
We played with the contrast of the picture and we think the first "u" looks like it is actually an "M". 🤔
No, it's lower part is missing. Same for the B. The text says ~G?S DUISBURG. I can't decipher the name of the company completely ~~, probably RHEINGAS.~~
What sound does it make if you hit it with a stick?
What happens if you light it on fire?
We rapped on the side and it felt very solid, we didn't think to whack it with a stick.
I would say that a sledgehammer would be the right tool here.
Boba fett vibes
Green is usually for Argon or other inert gases.
It's red underneath
What is this thing?
Let us help you identify that mysterious object you’ve found.
Currently in CHALLENGE mode: If you've got something obscure knocking about, post a picture, and let's see how we do. Please prefix such posts with "CHALLENGE:" so we know we've got a fighting chance.
