Lithium Polymer batteries (LiPo), are a relatively newer type of battery now used in many consumer electronics devices. They’re pretty similar to the better known Lithium Ion batteries. They are generally lighter and pack a bigger punch than older technology batteries like NiCd or NiMH.
As extra batteries for my little Hubsan I got some 3.7V 380mAh LiPO batteries (https://smile.amazon.com/gp/product/B00RZ1G3NU/ref=oh_aui_detailpage_o00_s01?ie=UTF8&psc=1).
The 380 is the capacity and the 3.7 is obviously the voltage. These are relatively small and I haven’t started to worry about C ratings. From what I’ve started to read, there are some dangers for fire when using LiPo batteries. So most people recommend never to charge a battery unattended, look for bulges or signs of damage, and even a fireproof bag for safety.
I might eventually get a bag or maybe just a metal box, but these tiny 380 sized ones don’t look too concerning at this time. I have started to research them, but I haven’t decided on one yet. While a bag looks to be cheaper and easier to handle, an ammo case or fireproof safe just look cooler. We’ll see what I decide on.
There are plenty of warnings not to store them at full charge and to also never fully discharge them. A lot of the safety measures seem to be built in, but it is good to be aware of dangers. Bottom line I think is to be careful and just have your eyes open for any warning signs.