I left a review shortly after I received this item (which I got to replace my original charger that I left in a hotel room) singing its praises for being £20 cheaper than one from Apple yet being the genuine article.
I was wrong.
It failed within two months. The MagSafe connector developed a loose wire and stopped working altogether after a couple of days.
I immediately went to an Apple accredited Reseller and bought a genuine Mac charger and compared the two items. I was disappointed to discover that the cheaper one was not genuine. It's pretty close - you can only tell when you have it up next to a genuine one - but definitely a knock-off.
To be fair to the seller, when I requested a refund I got one. Eventually. At first there was an "administrative error" that meant I was sent a replacement but in the end I got my refund in full.
Suffice it to say, there is a reason genuine Apple product are so expensive - they work.
DO NOT BUY this knock-off, it's a false economy.