This is a high quality battery pack, I love it because my truck does not have good charging ports and my phone is always dead when I get off work. I can easily plug one of these 2 5200mAh batteries into the Q-Swap module and power up my cell phone.
These devices are around 5 oz each and are very sturdy and about the size of a deck of cards.
I use mine all the time – especially when I am out shooting video.
I will admit they are expensive, but they are very high quality. If you use a lot of electronic devices ity is nice to have such an easily used and easily charged system to ensure you can always have power.
It is much more expensive than my DIY mason jar batteries, but it is infinitely nicer.