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It appears to be 1333 Ram, but I don't speak Spanish so can't really say for sure
 
It has the same part number as that recommended by Kingston in their configurator for the 13" MBP 2011 so it looks like this is the right part. You will, of course, need 2 of them if you are upgrading

Thanks a lot!
I will probably buy that since I am in Italy and it is an italian seller!
Kingston should be a good trademark, ins'nt it?
 
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