To my S4 battery (2600 mAh) invites the amzdeal battery theoretically slightly more than 3 times. Practically I have my cell phone (battery at 20%) charged on average 4 times. Charging the battery itself is quite fast and do is done in 4 hours.
As an encore to the battery a practical and simple protective sleeve and an elastic band is supplied. The protective sleeve has a magnetic closure and protects the battery during transport quite reliable. The rubber band will probably serve to fix the battery to the zuladenden devices, but somehow I find this unnecessary.
The only criticism is I liked the eye, is the charging cable. It is with its just under 22cm for my taste too short.
Conclusion:
Who travels a lot, his phone must have always online, has no outlet nearby and therefore the idea is something plays in addition power for his cell phone to obtain is the right place for the battery.