I was at the market today and bought what I was told was a new wireless keyboard and mouse only missing the unifying receiver which I have one. The price was excellent, I was very Excited until I got home and unboxed it and took out of plastic. First I noticed that it seemed to have been used and saw dust and a bit of grime on them. No problem, I cleaned them up. Next I noticed that the keyboard was a k350 and the box was for an mk550. No problem, I actually like the k350 better. So I went to Logitech site and got the unifying software – put batteries in keyboard and mouse. Mouse worked fine, I actually have same mouse without a back cover, I was a bit happy now had 2 of the same mouse and a back cover that will fit on both so has a backup mouse. I turned on the keyboard and it seemed to be working, and then noticed that only about 90% of the keys worked. Hmmmmmmm, So I took the keyboard apart and was obvious then, they had spilt something in keyboard and it fried a bit of the circuitry on the plastic sheeting. Obviously they had bought a new mk550 keyboard and mouse because had broke their keyboard and put the old keyboard and mouse in the plastic and in the new box. They kept the unifying receiver as those things cost about $10 and always nice to have a backup. The price I paid was low and because I work on computers can use the keyboard for parts. I have a k350 keyboard that I used for a year now and am using it now and now have all the spare parts except the plastic sheeting circuitry. That is not the point however. They seller boldly set out to deceive, boldly lied, and did so for a very small amount of money. The lesson was for me, God reminding me not to even tell a small lie, full disclosure when selling, do not be like the seller that did this to you. Be better…. smile emoticon