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.