I would say they're best for kids 11 yrs and older. Probably a bit imature for a seasoned Christian! They are titled New International Readers version.
I found the following description of this exact bible on the www.biblicadirect.com website:
Now there's an even more affordable option for evangelism to kids. New International Reader's Version (NIrV) Bible text is written especially for children. It is written in an easy-to-read Bible format combined with color insert pages with Bible illustrations and call-out scripture passages. The bright cover and 24 color inserts located throughout the Bible draws kids into the book. This paperback Bible is light and easy to carry. Ideal for children ages 6-10. 1,344 pages. (5-1/4" x 8-1/2")