Suitable adapter for a battery extended pack?

I purchased a battery extended pack today at Noel Leeming. It is a Lenmar battery pack with 7000 mAh as capacity. However, it only came with a USB cable but there's no adapter for charging. My question is I have an Ipad 4 adapter and an Iphone 5 adapter, I wonder if I could use 1 of them to charge my battery pack safely?

This is the information about the batter pack:
Input: 5VDC -- 1A
Output: 5VDC -- 1A, 2.1A
2USB ports for Phone and Tablet charging at once

I'm looking for your answers soon

Are you sure you read the instructions correctly?

Lenmar products usually comes with TWO USB ports… One labelled IN, and the other labelled OUT.

The IN port is for charging the battery pack from appropriate USB power ports.