This 4s 14.8v 980mAh Battery is very slim, extremely lightweight battery, based on Lithium Ion chemistry. All cells combined gives output 14.8V with current capacity of 980mAh! (arround 1000mAh).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.