This is lightweight carbon fibre tube.

8mm outside diameter, 7mm inside diameter, 0.5mm wall thickness. 

Weight 20 g/m

The tube is pulltruded tube which means the fibres are all directed down the length of the tube. This is stronger than woven tube in tension but has lower torsional strength and stiffness. 
The surface finish is matt black. 
This is sold in 1 metre lengths. 
Note: Image may be of a different size tube