Anker is supposedly a company you can trust with making batteries. It works as expected, wish there was an indicator for how much charge it has left though. It has a disclaimer inside that says expected loss of energy due to thermals and transfer efficiency is about 30% which is lower than the industry standard 35%. So don't expect 3000 mAh, expect around 2100mAh but this isn't the only company that you will get reduced mAh that the stated. Good enough to charge your mobile from 0-100% once as long as that battery is 2100mAh or lower, still the portability is what this power bank is going for so in regards to that case, it does well. Not to mention, its really well built.