Polypropylyne or rubber channel

[EWG]

Ladies and gentlemen,

Can I have some advice and information please.

I need to buy 4 metres of rubber/plastic or polypropylene "U" shaped channeling 55mm wide by 20mm deep but it must be in black.

Does anybody have any idea where it can be bought?
Here's a photo of what I need :

This particular one is made in Germany I believe.
The internal rib you see is not really needed and can be cut off.

Any ideas everybody?

Thank you