I first used it while walking around with a USB battery pack and an iPhone. After about 20 minutes I found that my phone was no longer charging and that the Lightning adapter had just slipped off the end. I put it back in and it quickly happened over and over again. The phone charged for a short time and then stopped charging as soon as the adapter slipped even slightly off the end of the cable. I also had an Android device that used USB-C, so I tried that too and had the exact same issue. I don't see any obvious defect in the cable I received but there is nothing other than the friction that keeps the adapter on the micro USB end and at least with what I received it's not enough if the device is moved. However.