Very poorly finished 2

Usually it is because of the trapezoidal shape of the micro-B connector impossible to plug the wrong way round in a device to stick. Here, this is not the case. It is possible to plug the adapter in both directions on the Micro-B connector without effort. With the result that if one upside been attached him, the USB supply voltage polarity is reversed for the following unit (+ 5V comes to GND and GND to + 5V). At best, the USB device is then no Mux by itself (if the device has an internal reverse polarity protection, which is often not available because it's usually impossible mechanically operates a USB plug stuck around). In the worst case, then the USB device is broken! (Toll how to destroy an expensive USB device (digicam, mobile, ...) with a 3 Adapter ...
Oh, in addition to the short-circuit problem, the mini-B connector of the adapter devices Very much in div.. For example, my SanDisk Sansa MP3 players now on the metal jack numerous scratches. When I pulled off the adapter again, I could only times wegpusten small metal shavings ...