I bought this set of two blocks cause I figured it was a pretty good bang for the buck. One of them I used for home use, the other was sitting around doing nothing for about a month so I decided to bring it to the main office at work as we were in need of one. I was pretty surprised when about two weeks after bringing it over when I actually used it for the first time, I discovered that it didn't work at all. Both USB ports using cables that I knew worked on outlets that worked for a different block. Nothing. I asked a coworker, and they said it never worked. I don't recall if I ever tested it before bringing it over to work, which in hindsight was a bit of a "duh" moment on my part.I know to assume someone might have somehow busted it isn't out of the question, but I'm not quite sure how they would have done it in at most two weeks. The outside is completely fine; no sign of damage or evidence of someone opening it up, plus I can't see any coworkers really doing anything intentionally to break something like it.So, a possible quality control issue? Could be. Do what you will with this information to make your own conclusions. I'm inclined to suspect that this particular block was maybe just a bad batch from the factory, which is why I'm giving it the lowered stars.But all in all, the one that does work is pretty good. Charges every device I connect to it at a good speed, even with two devices plugged in. Haven't had any issues at all with the one that works. Had both blocks worked, this would have easily been a solid 5 stars.