This is lightweight carbon fibre tube. 6mm outside diameter, 5mm inside diameter, 0.5mm wall thickness. 

Weight 14 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.