If you hover over the " Sizes Available" a tap will appear and provide you with the correct age sizing.
I feel your frustration, that's why I included my son's age along with the size. He is a small guy, 6 years old, and the small gloves fit him perfectly. I may have ordered a medium so he had room to grow. So I would say the small is appropriate for a large 4 year old up to a small 6 year old.