Regarding Power Bank for iphone 5s55

I am from india I would like to buy a power bank which is afordable for me.

My charger gives a output of 5V/1A to my iPhone 5s.

But the power gives output of 5v/2A or 7v/2A or 12v/1.5A description in power bank says that it can detect phone voltage and current range of phone and can give output according to that.

So whether it is safe to use that or not.

This is link of power bankhttp://m.buy.mi.com/in/item/3174300006/?RNType=product&product_id=3174300006#pro duct

Please help me.