This product is poorly made. There are no approval marks stamped on the plug and the live & neutral screw heads are too small to allow proper connection of the cable wires. I think under 10amp full load it would overheat. Additionally, it was a loose fit when connected to my TV and the power connection was intermittent. Don't waste your money on this product, mine ended its short life in the dust bin.
The battery arrived in sealed packaging and when I put it into my Sony A57 it worked without problem and the camera reported its charge state without problem. An excellent saving against the over priced original Sony battery.