4 stars instead of 5 for just one reason: my wired mouse died, the reviews for the wireless mouse were good - it's a B&D product after all - so I bought it. I have a carpentry shop at home and was finishing a project when my old one died. I charged the battery for about an hour before using it and I don't think it lasted half an hour. A full charge overnight gave me maybe an extra half hour. True, I had a lot of follow-up work. Everything stays in order with this backup battery. Do yourself a favor, spend your extra money and buy an extra battery.