The ordering interface does not display sizes in the size chart and the sizes in the ordering interface do not correctly reflect the actual size of the socks. I ordered a size "9-11 years" which is not in the size chart and does not match anything in the size chart. But my kids are that age, so I went along with it. The socks I received are actually marked "Large" and "Shoe Size 6-9", which is significantly larger than the largest shoe size every 9-11 year old I know wears and which, more importantly, does not correlate with the size chart. After looking at the sizing chart and drop down menu on the order screen, it's a complete mystery as to how to get the correct sock size. Looks like good socks though. It's not clear if I should return them or weigh them for five or six years until my kids grow up with them.