Having recently bought a MacBook while in the States, I needed to order a UK adapter in order to use it at home. This does exactly as it states. I've had no problems and I am happy with my purchase. I would recommend this to anyone in a similar situation.
The only thing I will say is that this is the extension cable, not the standard shorter power cable. I knew this when buying so it isn't a problem, I'm just stating it for other buyers so they are certain about what they will get.