The sizing is basically for toddlers -- one year to five or so -- but you could make it larger or smaller by removing repeats. The stitch pattern is a multiple of 8 plus 1, which means each time you add or subtract a repeat you gain or lose almost 1.5 inches in width on each side of the garment.

This pattern was on About.com (which no longer exists) and has been deleted from their site, but for now it can still be found on the Internet Archive. They redirect and delete pages a lot so you may want to download/print to save.