Unfortunately, there is no practical way to test a travel adapter until you are in a foreign country and need to plug something in. If it doesn't work, you are then stuck in your hotel room with devices that can't be used unless you go out searching for a store to buy a new adapter. That is what happened to me. I intended to use this adapter to charge my laptop and iPhone simultaneously on a trip to the UK. The USB charger port never worked at all. The USA AC plug worked briefly, but then it made a popping sound and stopped working completely. I just threw it away. It wasn't worth packing home to try to get a refund. The cost was trivial, but the inconvenience was much greater than the money lost. I wish I had paid a few more dollars for a reputable brand instead of trying to save money with something cheap.