This product called little comment.
It is simple to use: plug your micro-USB cable into it, then connect it to the socket "Dock" of your Xperia and the battery light begins to light and the phone starts charging.
Unlike others who use the same type of product, I have no worries about the charge: charging is quick and equivalent to a standard USB cable.
However, like others who use such products, I have a concern about the strength of the magnet. But I think the product itself is not in question ... In fact, not having the chance dropped on a metal part, really had to pull it off the back. So I have the impression (to be confirmed) that this is the next smartphone metal piece that makes the magnet remains poorly established and disengages as soon as you move a little ...