This very small bag is excellent for my diabetic grade-schooler.  He must keep a few emergency supplies with him at all times, and this little bag holds those things easily, with a little room for extra stuff when we have a longer outing.  But the small size of the bag makes it so that he's not toting something huge around with him all the time.  This is small, neutral-looking (meaning it doesn't look like a "medical kit"), and does the job.