You have finally found one of the most versatile insulated bags around, said to have over 1000 uses! Used as a lunch box, it is great for all ages, and the perfect size to hold a full lunch. It is easy for kids to carry, or can fit perfectly in a backpack for school.
The insulated square is also great to hold:
portable game systems (Gameboy or DS and game cases)
snacks in the car or plane
things kids collect at home or on vacation (shells, rocks, anything fun)
homemade treats and a thank you card or encouragement card as a gift for a friend or teacher
Keep it handy... I am sure you will find many other uses for it. Makes a great gift for any age, and it can hold extra gifts inside (and even a small card).