Brake pipe diameter?

[spannerrash]

Hello, hope you are all well.

Does anyone know where I can buy the black coated hard brake pipe fitted to the 8s. I have a small sample which is a genuine part from main dealer and it seems to be 5.1mm outside dia.

Give me a little latitude as I was using a manual vernia to measure and my eyes aren't what they used to be but it is definitely not 4.75mm which is more common.

I actually ordered some 4.75mm green plastic coated just to double check the size and it is definitely smaller. You can measure it and even feel it's different with your fingers.

I know there will be other options but want to keep the car as original as possible so black plastic coated would be my preference.

Can anyone point me in the right direction?

Thanks Frank