using a microscope I can see the piece of carbon fibers of around 0.2 mm in length (at 150x zoom) in a translucent PETG, I would have hoped for 0.5 mm long but the filament is easy to use, maybe easier than PETG only filament, I print on blue tape. The printed pieces look black mostly matt, I guess the carbon fibers absorb most of the light. This filament is certainly a good product I would likely recommend to buy. I certainly will buy more from the seller when I needed.
Easy to print PETG-CF with an E3D hardened nozzle and a direct drive genuine BMG extruder. So I ordered two other rolls. One week to arrive to France, fast delivery!