iWalk Duo 3000 costs mere 25 dollars and is cheaper and lower capacity version of the iWalk Extreme Trio 10000 battery. This battery can be used to charge your iPhone or any other iOS device as it comes with lightning cable built in. If you own a non-iOS device, you can charge that as well as it has micro USB cable on the other side. We reviewed iWalk 5400 universal battery charger nearly six years ago and it is still working so we can vouch for iWalk Duo 3000 as well.
To charge it however, you must use a micro USB cable. You can also alternatively use a micro USB charger. There is a small LED light on the front and iWalk Duo 3000 can charge your iOS device at 1A charging speed. You will be able to charge your iPhone 6s fully from 0->100 percent with this iWalk Duo 3000 with some juice left for next recharge.
There are not many USB chargers out there with built in lighting cable that cost so less. iWalk Duo 3000 costs 25 dollars and comes in black, gold, silver and white colors. [product page]