Ordered a M310 optical mouse; the dongle was hidden inside next to the battery, and literally *camouflaged* to blend in with the rest of the inner space. I noticed later that the pictorial instructions did make note of this placement, but with such a simple device, who the *** would bother to look at the instructions? What the *** are they thinking? They're trying to be way too clever and for no reason whatsoever. User's recommendation: Always assume the designers of these products have their heads up their ***.