This is by far the best combo for the price you will find(unless you get into rebates of course). There is no lag and both the keyboard and mouse are responsive and work great from at least 15 ft. away from the transmitter(was actually in another room while typing something to test). It is OEM but it comes with batteries and a manual so I can't see the difference between this and retail packaging except the fancy box. It also comes with a 3 year warranty.
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