Very useful for travelling purpose .Handy and easy to carry , especially helpful for train or bus journey for more than 8 hrs. Now a days everyone use smartphone and battery backup continued upto 7 to 8hrs on avarage so a good powerbank is very important. Though train or bus may supply charing point for mobile or tablet but all those are not safe for high priced gadgets.I think Ambrane Power Bank is best to use.