Frustrating POJ...Ripping open the sealed plastic package is the only thing that works with this product, because of the pre-cut opening. That doesn't matter, because the product doesn't work: Popped the included batteries into the mouse (correctly), and inserted it's USB dongle into a USB slot. Windows reports it didn't install correctly and the device may not work properly. No kidding, because - in addition - no light emanates from the "high performance laser" (that's what's printed on it, no kidding!) I then tried three other slots with the same abysmal install results. After turning the mouse on/off switch on, to see if - at least - the laser in the mouse made light, I was right about that suspicion too. Dead donkey. I measured the batteries voltage which was fine, and even tried other, new batteries without any improvement. I returned this POJ, and went back to open another one in the store, going through all the same steps (except the USB dongle). That laser was dead too! The entire box of mouses don't work. No wonder this is on sale. In fact, Costco and Logitech should PAY ME for my time and gas wasted on this stupid product trying to get one to work. Using a ten year old mechanical mouse for now, made when products weren't complete fails, until I can order a simple, $2 wired, optical mouse. DON"T WASTE YOUR MONEY ON THIS JUNK! This posting will end up on my ten global consumer websites in four languages (read by about 310,000,000 readers) as a prominent Southern California Consumer Advocate.