I bought this 20k mah MI power bank before 3 months.It is a very useful electronic gadget and not once youll regret buying it.I use it for charging my samsung J2 pro’s 2600 mah battery and i am able to charge my phone fully for 7 times.Im not a tech freak but the only thing i find very irriating is the time it takes to get charged.To get fully charged it takes around 1 full day yeah!a solid 24hrs.It has got 4 led white lights to indicate the amount of power present in it.It has got a button in it.It should be pressed for charging relatively smaller equipments like bt headset and handsfree.One more good thing about this power bank is it has got two usb ports for charging two gadgets at a time!On the durability part i highly suspect it beacuse its not even 4 months since i bought it but it has got awful scratches on it that makes it look more like an year old.It doesnt come with any charging cables or whatsoever.Overall id give it 3.5 star rating out of 5.