These batteries work great! They're easily recharged within several hours via any USB connection. There's no need for a separate charger, which I find the most prominent feature compared to other kinds of rechargeable batteries. Each USBCELL has a small LED light indicating whether it has been fully charged or not. It's solid green (indicates charging) and blinking (indicates a 90% charge). Easy to travel with, easy to use and cool to charge! If you have something you always need batteries for (such as a wireless mouse like me) and do a lot of computer works then these are an excellent investment. The price tag is a little steep but I thing the convenience makes up for that. They come in a pack of two and the USB ports of some computers are too close to charge them both at the same time. In that case you need the help of an USB extension cord or an USB hub. The idea of reducing carbon footprint behind these batteries is also great!