I have both that keyboard and that mouse.
The mouse, although not optical is good and feels comfortable. It is indeed a Logitech OEM.
I like the keyboard too. It has class. However i should point out that, its tactility level is low even for a rubber dome.
I have tested it NIB (a coworker bought it new) and even then the rubber felt soft and the key travel short.
Also the keys rattle a lot. They rattle so much one could be misguided by their sound to believe that the switches are mechanical.
Last but not least, DO NOT buy it from that specific seller. I bought mine from him.
When he says MINT condition he means pretty clean with no scuffs. Do not confuse mint with slightly used.
I specifically asked him if the keys felt mushy. He avoided to give me a straight answer and said that he would send me the best of his lot.
If what i got is the best of his lot you should avoid his lot. Mine is really broken down by use.
There are keys that feel like pressing on folded rubber.
It is clean (very slightly yellowed), no scuffs, fully working, but ...