I want to replace the main support pole or tube with one approximately 15mm/0.6" taller. The diameter is 35mm and the internal thickness seems to be 1mm. The listing on Amazon mentions it is steel but it is not any more specific than this.

I am unsure if I should be searching for a certain type of tubing, or one with a particular durable black finish, or apply some black metallic paint. Also uncertain if any kind of steel will do and if using a solid pole instead of a tube would be okay or put too much pressure on the steel/die cast metal desk clamp.

What should I look for here and where is a good place to order from? I am in the EU but I can order from the UK, US, or elsewhere if necessary.