These are very slim, extremely light weight batteries based on Lithium Ion chemistry. Each cell outputs a nominal 3.7V at 600mAh! Comes terminated with a standard 2-pin JST-PH connector - 2mm spacing between pins. These batteries require special charging. Do not attempt to charge these with anything but a specialized Lithium Polymer charger.
Please use caution when using this battery in wearable projects. When using conductive thread, a short in the thread can create sparks and heat. We recommend using coin cell batteries for beginners.
Note: Be careful with the JST connectors. They can stick in pretty good and tugging on them can damage the connector.