These are replacements for the stock batteries that came with the T-Mobile watch. Those batteries expanded, separating the watch cover. I had two T-Mobile watches (twins) and they both happened at the same time. I am hoping that these replacements have a much better performance. Although, the kids might not have them as the want to upgrade to phones (ha ha). So, I can't judge the actual batteries at this point. What I can judge is the time for delivery, and that's why the 4 Stars and not 5. I paid the extra $8.95 for 2+ day delivery. It took over 2 weeks to receive the order. Not happy, as my kids were without a way of communicating in case of emergency.
