Somewhat annoying is that apparently the low cable cross-section (as the price of the actually smart roll-function) the resistance increases such that my Multi-Bay-BlueRay / DVD drive /...- it is not working. Only once I managed to drive an audio CD. One should therefore consider beforehand (I was not yet clear that a Super Multi BlueRay drive obviously requires more power than an external HDD - one thinks of BlueRay, one can but imagine the). For the usual application for connecting external HDD the cable seems to work well but - and is not meaningless when rolled around.
Conclusion: For my application (I want to temporarily connect to the home BlueRay / DVD-Multi, while also the second battery in the multi-bay charging) will I still procure an additional cable without retract function. But the part described here I keep happy.